Toadstool: Mushroom-Inspired Rocking Stool

Introducing: Toadstool! A mushroom-shaped stool on which you can sit, rock, wobble and spin. Its smooth curves, radial symmetry, and rounded form are inspired by none other than the humble mushroom.

For context: I tend to fidget and move around a lot when I'm sitting down and trying to work at my desk. So, when I first started brainstorming for this project, I knew that I wanted to make a cushioned rocking stool that enables me to fidget freely and shift my posture. And eventually, the rabbit hole of sketching, brainstorming and bodystorming led me to this mushroom-inspired functional form!

Before we jump into it, I'll explain a brief overview of all the stool components. The stool is made up of a wooden base and a removable pleated fabric cushion.

The stool's wooden base:

• The base of the stool is made out of wooden slices that slot together, which I cut out of 1/2-inch thick plywood on a CNC milling machine.

• I designed the wooden base using Autodesk Fusion 360 and the Slicer for Fusion 360 plugin, which allows you to take any 3D model in Fusion 360 and transform it into various configurations of flat slices that slot together.

The stool's removable pleated fabric cushion:

• I sewed the cushion out of a sturdy orange canvas fabric using a sewing machine, and added some finishing touches with hand embroidery.

• The stool's pleated cushion is removable, so you can take it off and throw it in the washing machine. I decided to make it removable because the cushion cover is pleated, and I was worried that dust would accumulate in the pleated crevices over time. Plus, I can't trust myself to not stain it!

• The pleated pattern and design process was inspired by origami folding techniques. Since I wanted extra precision for the origami-like pleats, to make sure all 13 pleats line up at the center, I cut the fabric using a laser cutter instead of scissors.

Now let's get started!

Tools and software for designing the stool's wooden base:

Software:

• Autodesk Fusion 360
• Slicer for Fusion 360 plugin

Tools:

• CNC milling machine
• Laser cutter
• Rubber mallet
• Orbital sander
• Clamps

Materials for building the stool's wooden base:

• 1/8-inch thick plywood for laser cutting the mini prototypes
• 1/2-inch thick plywood for the final stool base (I used a bit more than half of a 4' x 8' ft sheet of plywood)
• Wood glue

• Sandpaper

Tools and software for designing the stool's pleated fabric cushion:

Software:

• Autodesk Fusion 360
• Software for setting up your laser cutter file (in my case, I used Adobe Illustrator)

Tools:

• Sewing machine
• Serger (optional)
• Laser cutter (optional)
• Pencil
• Ruler
• Scissors
• Iron
• Ironing board or a safe place for ironing fabric
• Embroidery needles for hand sewing
• Sewing pins
• Spools of thread that match your fabric color

Materials for the sewing the stool's pleated fabric cushion:

• Thick canvas fabric
• Additional fabric as lining to hold the stuffing inside the cushion (I used scrap muslin fabric)
• About 18 inches of 1/2 inch wide elastic
• Polyester stuffing or a small circular pillow

The king oyster mushroom, which also goes by its scientific name pleurotus eryngii, is one of my favorite mushrooms to eat, and it also has a rounded shape on both its top cap and bottom. So, it felt fitting to use the king oyster mushroom as inspiration when designing the form of the rocking stool.

I started out by modeling the mushroom shape as a 3D object with Autodesk Fusion 360.

Sketching the 2D stool silhouette in Fusion 360

First, I created a 2D sketch of the stool's silhouette in Autodesk Fusion 360, which I drew by connecting points with curved splines to create the shape of half of a mushroom's cross section. You can see this sketch in the 1st image above. I used Fusion 360's mirroring function so that I only needed to draw one half of the mushroom shape, and then Fusion 360 would symmetrically mirror the curve across the central vertical axis.

Turning the 2D sketch into a 3D object

Then, to make the 2D sketch into a 3D object in Fusion 360, which is pictured in the 2nd and 3rd images, I revolved the 2D sketch around its central vertical axis in 3D.

Dimensions of the stool base

I decided on the stool dimensions based on what I thought a comfortable stool size would be for my height. I am a rather short human in stature, so I decided on a 16.5 inch tall stool as the total stool height. The diameter of the stool top is 14 inches, and the diameter of the stool's curved base at the very bottom is 12 inches. The middle curved portion of the stool, where the mushroom form is the thinnest, is 8 inches in diameter.

Fusion 360 file

If you'd like to play around with my Fusion 360 file yourself, here is the .F3D file. You'll need to install the Autodesk Fusion 360 software in order to open and navigate around the file yourself, which you can install here at the Autodesk website!

As the next step, I imported the stool base model into Slicer for Fusion 360, which is an awesome plugin that allows you to "slice" 3D models from Fusion 360 in a plethora of ways so that you can fabricate them out of flat material.

Exploring different slicing configurations with Slicer for Fusion 360

When you slice a 3D model in Slicer for Fusion 360, the outputted slices give you the option of having slots cut into each slice, and it also numbers each slice so that you have an easier time figuring out how to assemble the pieces together. It also conveniently arranges the slices according to your specified material dimensions, so you can quickly prototype your slice configurations with your laser cutter or CNC mill while minimizing material waste.

I tried out a bunch of different slicing configurations: I tried both radial slices and rectangular grid-like slices. I also tried adjusting the orientation of the X, Y and Z axes to "twist" the slices around, so that they aren't exactly parallel or perpendicular to the mushroom form's central vertical axis.

Prototype design files

Once you're ready to actually fabricate your sliced designs, you can export your files from the Slicer for Fusion 360 as various file types, such as EPS and DXF. Since I planned to prototype my sliced designs using a Universal Laser Cutter, I decided to export my sliced design prototypes as EPS files, which I've included here for you.

As the next step, I created a few laser-cut prototypes for the wooden base.

Prototyping different slicing configurations with the laser cutter

After trying out more than a few different slicing configurations in Slicer for Fusion 360, I exported the file so that I could see how they look and feel in my hand as mini laser-cut prototypes. I also wanted to test the wobbliness of the rounded curve at the bottom of the stool base. I laser cut the prototype files out of 1/4" plywood using a Universal Laser Cutter, to see how different slicing techniques looked.

You can see 3 of my laser cut prototypes in the 2nd picture. The ones pictured here are some of the successful ones, but I had more than a few failed prototypes too where the slots couldn't fit together, since I didn't properly calibrate the laser cutter. I would recommend doing some test cuts before you cut your final prototypes to save yourself the time, stock material and the headache!

The final stool base design

In the end, after testing out several prototypes, I decided on a slicing configuration that consists of 13 vertical slices, and 2 circular disks that hold the 13 vertical slices together. I thought that this slicing design best showcased the round curves of the mushroom form. I decided to only use 2 circular disks to hold the 13 slices together, to minimize the weight of the final stool base, and also to keep the emphasis on the smooth curves of the mushroom silhouette. I also thought that it echoed the look of an actual mushroom's gills.

After finalizing the design and file for the slotted slices that make up the wooden base, I cut out all the pieces out of a 4 ft by 8 ft sheet of 1/2 inch thick plywood that is finished with maple veneer. I fabricated this using a Shopbot CNC milling machine. I am super grateful to have had access to a well-equipped makerspace that had all of these digital fabrication tools, which felt like gaining a whole roster of new superpowers to a humble beginner like me!

Designing the CAM tool path in Fusion 360 to cut the stool base pieces on the CNC mill

When you design your CAD files (which stands for computer-aided design) in Fusion 360, you also have the ability to define the manufacturing process by generating the CAM files (which stands for computer-aided manufacturing). In my case, this means that I can set up the entire machining toolpath in Fusion 360. Then, Fushion 360 uses this toolpath to generate a gcode file, which I can send to the CNC milling machine as its instructions for how to manufacture my stool base pieces.

The first image here is a screenshot of my CAM file in Fusion 360, where you can see some color-coded lines that convey the different CNC milling tool pathing processes. For example, the blue lines indicate the outlines of the "2D Contours", which are the paths where the CNC mill will cut all the way through my material. The yellow lines indicate where the CNC mill's end mill bit (which is the metal bit that spins rapidly to cut through the material like a drill bit) will lift up into the air to travel to different places on the stock material before cutting.

Simulating the toolpath in Fushion 360 before you start cutting with the CNC mill

Before you start actually cutting your design out of wood on the CNC mill, you can first run a simulation of the fabrication process within Fusion 360. This allows you to double check your CAM file to make sure everything will run smoothly, and it also shows you the estimated time it'll take to run the whole cutting process.

For me, Fusion 360 estimated that it would take me about 40 minutes to cut everything out of wood. In my case, that estimate was quite accurate when we only consider the actual cutting time! However, overall, including file setup time, the cutting, and clean up time, it took me about 2.5 hours total to finish cutting all of my wooden pieces on the CNC mill.

Sanding and finishing the wooden slices

After I finished cutting out all of the pieces, I sanded away all of the rough edges. I started off gently smoothing the edges with an orbital sander, then finished it off by smoothing the edges with finer grit sandpaper by hand. Since I used plywood with maple veneer, I didn't need to sand the faces of each piece, but I recommend that you sand the faces if you don't use pre-finished plywood like I did.

At long last, the fun part: putting all the slices together! When I cut the wooden pieces on the CNC mill, I made sure to do a test cut first to make sure that the slices slot together snugly. This snug slotted fit meant that I didn't need to use any wood glue to hold the slices together. I used a rubber mallet to help nudge each piece into its respective slot, without damaging the wooden pieces during the assembly process.

Thankfully, each of the 13 radial slices were identical, so it was easy to immediately identify where each piece was supposed to go. I found that the easiest way to go about the assembly process was to fit each of the 13 vertical slices onto both of the slotted disks one-by-one. You can see how that process started to unfold in the first image, which shows how the stool base looks after fitting 5 vertical slices in.

The 2nd image here shows how the final stool base looks after putting all the slices together! And the third image is a bird's eye view of the base's top.

As the next step, using a bit of wood glue and whole bunch of clamps, I attached the circular top of the stool to its base, and left it overnight to dry and fully harden.

To prop up the stool so that I could freely position my clamps, I first put the circular stool top on top of a separate mini stool, which you can see sitting on the ground underneath the mushroom stool base in each image here.

Next, with the help of a friend as an extra set of hands, we carefully positioned the stool base upside down on top of the circular top in the center. To act as a guide for positioning the stool base exactly in the center of the circular top, I sketched some guiding lines on the bottom of the circular stool top with pencil.

After that, I found virtually every clamp I could get my hands on to firmly hold the stool base to the circular top while the wood glue dries overnight.

And finally, after waiting at least 24 hours, I removed all of the clamps and voilà! The stool base is finished!

Now that we're done building the wooden stool base, it's time to make the comfy part: the pleated fabric cushion!

Prototyping the pleated pattern with paper

I started out by prototyping with large sheets of paper and fitting it over a circular shape, in order to figure out how I wanted the pleated design to look. You can see one of my paper pleating tests in the second image, which shows an asymmetrical design where the center of the pleats sit at the edge of the circle.

In the end, I decided to go with a radially symmetrical pleat design. This would help make sure that the cushion's shape stays rounded in the center once I fill the cushion with stuffing or a circular pillow. I also decided that a radial pleated design would better tie together with the radial design of the wooden base.

Designing the pleated pattern in Autodesk Fusion 360

After a few rounds of rough sketching on paper, I moved over to Autodesk Fusion 360 again to design the pleated cushion geometry. Since all of this would be sewn with fabric, I only needed to create my Fusion 360 design as a 2D sketch, which you can see in the 1st image here. The pleated cushion is actually made up of 2 halves rather than as one large circle — I decided it would be easier to handle as 2 halves rather than a single circle during the sewing process.

Dimensions of the final origami-inspired pleated pattern

If you look closely at the screenshot of the Fusion 360 file, you'll see there are solid lines that run from the edges of the circle towards the center. These are 11 inches in length, with a gap of 1 inch in between each solid line. I've included the Fusion 360 project file as a .F3D file so you can open it up in the Fusion 360 software and play around with the 2D sketch dimensions yourself.

In the third image, you can see my final pleating prototype, which I tested out on some scrap muslin fabric. This was the point where I decided to move on from the cushion prototyping stage to the actual cushion making stage. The process of making this prototype is the same as how I made the actual cushion, so keep reading to learn about the making process!

For extra precision and convenience, I cut out the pleated cushion pattern out of my orange canvas fabric using a laser cutter, rather than by hand with scissors.

As a full disclaimer, using a laser cutter to cut out your fabric template is completely optional. You could definitely just print out the template file on paper, trace it on your fabric and then cut it out with scissors. That being said, I was curious to try cutting fabric on the laser for the first time, and was pleasantly surprised at the results!

Cutting fabric on the laser cutter

To cut the fabric on the laser, I used a large Universal-brand laser cutter with really low power settings, to make sure I don't overly burn the edges of fabric. I did multiple test cuts first with the laser cutter to find the optimal settings for this. I also made sure to secure the fabric down flat to the laser bed with masking tape around the edges of the fabric, which you can see in the first photo.

Modifying the pleated pattern so that the fabric stays in place while laser cutting

Since the laser cutter has fans blowing around everywhere inside, I had to make sure that the laser cut fabric pieces do not lift off of the laser bed and go flying everywhere while the laser is still actively cutting. So, to get around this, I modified my pleating pattern's file in Adobe Illustrator by erasing bits of the edges all around the file. You can see the difference between the two files in my screenshots included as the 2nd and 3rd images. I've also included both files as Adobe Illustrator files: one with these erased bits as the file named "Radial Pattern with Cuts", and one without these modifications as the file named "Radial Pattern without Cuts".

Erasing the edges here ensures that the cushion pattern pieces always stay attached to the fabric material. Then, after removing the laser cut fabric from the laser cutter, I used a pair of scissors to manually detach the cushion pattern pieces from the rest of the fabric.

This step is all about preparing the pleats, before we start sewing them down! We need to make sure the pleats are nicely lined up, ironed, and straight, to make sure that each of the 13 pleats evenly meet in the center of the circular cushion.

For this step, you'll need a large flat surface where you can safely iron over your fabric, and also a bunch of sewing pins and an iron. You'll also want to use a pencil and ruler to sketch over the fabric first. Also some patience and music helps this meticulous task much more enjoyable!

Marking the pleats with pencil and a ruler

I started out by using a pencil and a long metal ruler to very lightly mark the lines of the pleating pattern. This will help act as a visual guide when you start ironing the pleats in place. You can see my pencil marks in the 3rd image here.

Pressing the pleats in place with an iron and sewing pins

Next, going pleat-by-pleat, one-by-one, I folded and ironed each pleat down, and then held the pleat in place with two sewing pins per pleat. This is shown in the 2nd and 3rd images.

The 4th image shows a close up of the pleats after I had finished pinning all of them.

The goal here is make each pleat quite neat, so that they all meet accurately at the center of the cushion. The 5th here shows the two sides of the cushion fit together, after I've finished ironing them and holding the pleats in place with the sewing pins.

Now that all the pleats are firmly held in place with the sewing pins, it's time to start sewing them down! We'll first sew down the pleats on each cushion half. Afterwards, we'll sew the two halves together to make one big pleated circular cushion.

Sewing down the pleats with a sewing machine

First, choose one side of each circular half that will be the outside of your cushion. To sew the pleats, you'll sew on the underside of the cushion. The first image here shows a completed cushion half where the pleats are fully sewn down, as well as the other half that hasn't been sewn yet.

I sewed a straight stitch all the way along the pleated fold on the underside of the cushion, at about a 3/8 inch away from the edge of the pleated fold. I left a little bit of room at the point where all the pleats meet in the center of the circular cushion, which you can see in second image here. I didn't want the machine-sewn lines to meet in the middle in a messy-looking way, so I decided to just leave it be for now. In the next step, we'll finish off the center point by hand-sewing the center in place.

Assembling the two halves together

After you're done sewing down the pleats on both halves, you can sew the two halves together to make a whole circle! First I used sewing pins to hold both halves together, making sure that the two fabric pieces line up each other consistently as a single circle. You can see how I pleated them together in the third photo here.

Then I sewed the two halves together with the sewing machine, by sewing a straight stitch all the way across so the two halves meet. You can see the center of the cushion's underside in the last image shown here.

To ensure that the cushion fabric doesn't fray and unravel over time, I finished the edges of the fabric with a serger. As an alternative to using a serger to finish the edges, you can also use a normal sewing machine to sew a zigzag stitch along the edges of your cushion. Both would work just fine!

Finishing the circumference of the cushion edge with a serger

I finished the circumference of the cushion, all the way around the circular edge, as well as the two edges where the cushion halves meet. The color of the thread doesn't matter, because it will be on the inside of your cushion anyway, and so you won't see it on the finished cushion. In my case, I used black thread to serge around the circumference of the cushion.

Finishing the inner portions of the pleats where they meet in the center

There is also the point in the center of the cushion where all of the pleats meet. I used a zigzag stitch on a normal sewing machine to finish the small unfinished portions of pleats on the underside of the cushion. In this case, I used a thread color that matches my orange canvas fabric color, just in case I made a messy mistake that causes the finishing stitches to show up on the visible top side of the cushion. You can see this depicted in the first image below this step.

To hold all of the 13 pleats in place at the very center point of the cushion, I hand-sewed them all together with an embroidery needle. I made sure to use a thread with a color that matches the orange canvas fabric, because this hand-sewn part would show on the visible top side of the cushion.

I stitched the 13 pleats together by sewing stitches back and forth across the radial center, almost like sewing a star shape. While I was doing this, I made sure to regularly check the top side of the cushion with each stitch, to make sure the stitch shows up neatly.

You can see the beginning of this process unfolding in the first image here, which depicts the center point of the bottom side of the cushion. It looks quite messy on the bottom side, but it doesn't really matter since that part is not visible. However, I made sure the top side of the cushion looks neat in the center. In the second photo, you can see the finished hand-embroidered center of the cushion top.

By this point, we've created the pleated fabric cover of the cushion. Now the next step is to turn it into an actual cushion by filling it up! In my case, I decided to fill my cushion with polyester stuffing, because that's what I happened to have on hand.

Cutting out a fabric circle to hold the stuffing in place

Before we can fill the cushion with anything, we need something that holds our stuffing in place.

First, you'll want to cut a piece of fabric that fits around the circumference of the wooden circular stool top. The stool top is 14 inches in diameter, so I used a circle (that I cut out of scrap muslin fabric) that was 14 inches in diameter. Keep in mind that once you fill the cushion with stuffing, the diameter of the circle will become a little bit smaller than the initial diameter of the flat fabric, due to the contraction.

Finishing the edges of the fabric circle to prevent fraying

After I finished cutting out the fabric circle, I finished the edges with a serger so that the fabric doesn't fray and unravel over time. Alternatively, instead of using a serger, you could also use a zigzag stitch on a normal sewing machine to finish the edges here.

Attaching the fabric circle to the underside of the pleated cushion top, leaving a small gap

Next, I sewed the circular edges of the fabric circle to the underside of the cushion top, making sure it was properly centered. I used a thread color that matches the orange canvas fabric, because this would be visible on the sides of the cushion. To do this, I used the straight stitch on a normal sewing machine.

In order to be able to fill the cushion, I made sure to leave a small gap of a few inches wide. It should be wide enough so that you can easily put your hand in the opening to place the stuffing inside.

Filling the cushion with polyester stuffing

Next, I filled the cushion with polyester stuffing until it felt sufficiently bouncy and dense enough as a cushion top. Keep in mind that over time, the polyester stuffing will compress, because you will be sitting on it. So it wouldn't hurt to add a bit more stuffing than you think is necessary.

Once you are done filling the cushion with stuffing, you can then close off that small gap that you left open in the previous step. You can either close it off by sewing it shut by hand, or with a straight stitch on your sewing machine.

Next, we'll add some elastic around the edge of the cushion so that it is stretchy. This allows us to easily remove the cushion from the finished stool, just in case we need to clean it or wash any stains in the future. Aesthetically, this also creates a "scrunched" look which further makes the cushion look like a mushroom top.

Choosing the elastic material and cutting the right length

As for materials, I used about 10 inches of 1/2-inch wide elastic. You can use a different width of elastic that you have on hand, or alternatively, you could even just use a piece of string that you tie together and then hide inside of the cushion, in a way that can be unraveled and removed later.

If you use a different width of elastic, keep in mind that the larger the width, the less stretchy the elastic is, and the piece will need to be longer. If you use thinner elastic like 1/4 inch wide elastic, that is a lot more stretchy, and so you may only need a shorter piece in order for your cushion to adequately stretch around the stool top.

To play it safe, you can always cut more elastic than you think you need. Then, once you finally finish running the elastic through the tube, then you can cut off any excess elastic as the final step.

Folding and pinning down the cushion edges to create a "tube" that holds our elastic

To hold our elastic in place, we'll fold in the edges of the pleated cushion cover and pin them in place, so that we can later sew it down. This will create a "tube" around the circumference of the cushion cover, which our elastic will run through. Since I used 1/2-inch wide elastic, I made sure to make my tube wide enough to fit the elastic through.

Since we are folding rounded edges here, the edges of the fabric will have to overlap in some places. To make sure that the elastic stretches evenly around the stool, I tried to evenly distribute the areas where the cushion edge's fabric overlaps around the circumference of the cushion cover. I used sewing pins to hold these overlapping areas in place. You can see this in the first two images above.

Sewing the tube in place with a sewing machine, leaving a small gap

Next, we'll use a sewing machine with a straight stitch to sew down the tube we pinned along the edges of the cushion cover. I made sure to use a thread with a color that matches the orange canvas fabric, because this would be visible from the sides and edges of the stool. You can see the finished sewn cushion tube here as the 3rd image above.

Instead of sewing all the way around the circumference of the circle to create an enclosed tube, you'll want to leave a small gap of a couple inches wide. This opening will be where you run the elastic through the inside of the tube, in the next step.

As our final step, we'll run the elastic through the tube around the circumference of the cushion cover, so that it can stretch around the circular stool top.

Running elastic through the tube with a safety pin

A handy trick for running elastic (or any string in general) through a fabric tube is to attach one end of the elastic to the longest metal safety pin you can find. Then, you can stick the safety pin through the gap of the tube, then gradually wiggle and slide the metal safety pin through the tube. This task would be difficult without a safety pin, because then you'd have to wrestle with the friction between two fabric materials.

Pulling the elastic through the tube to scrunch up the cushion fabric

Once you've finished pulling the elastic through the tube, you'll want to pull it so that the cushion fabric scrunches up like a mushroom top. The goal here is to connect the two ends of the elastic to make a circular loop, or an elastic band, around the edge of the cushion. You'll want to pull the elastic and scrunch the cushion enough so that the cushion is poofy and the elastic is taut, but still slack enough that you'll be able to stretch the cushion around the circular stool top.

Sewing the ends of the elastic together into a loop

Finally, once you've found a good length for the elastic band, you can either sew the two ends of the elastic together into a loop by hand, or with a quick back-and-forth zigzag stitch on the sewing machine.

Leaving the tube gap open for future repair

At this point, you could also choose to close the fabric tube by sewing it shut as well. However, I decided to leave the small gap in the tube open, so that I could easily replace the elastic band in the future. Over time, perhaps after several years, I find that elastic band material can sometimes disintegrate and lose its stretchiness. Planning ahead for our mushroom stool's maintenance and repair will save time in the distant future.

And finally, we are done! Our toadstool is complete! Now you can sit, wobble, rock and spin to your heart's content on your very own mushroom-shaped stool.

I had so much fun designing and building this project, and equally as much fun writing about it! Someday, I hope to continue iterating on this design to create a whole family of mushroom-shaped stools of different sizes, colors, and shapes.

Thank you for going on this journey with me, and if you decide to take the leap and make a mushroom-shaped rocking stool of your own, I would love to see it!