Magic Baby Fidget Toy

In this instructable I am going to show you how I recreated one of my son's favourite toys from wood and how to make a 3D printable version of it in Tinkercad.

The original toy is from the discontinued Lego Baby line (you can see a picture of it here). Both my son and I absolutely love it. To be quite honest, I probably fidget more with it than he does. So I decided to recreate it from a piece of firewood. The original mechanism is slightly different, but mine is easier to build and works great.

The toy has three poles that seem to be piercing through it. When you push one end of the pole, the other side will lift. Believe me, it is incredibly addicting, I love fiddling with it and so does my 13-month-old son.

This is also a great toy to teach math to kids since you need to know some basic geometry to design it.

Check out this gif to see it in action (it might take a little to load):

And here is another one to see how it rolls:

We will start by making the 3D printable version in tinkercad.

Start by creating a sphere. Simply select "Sphere" from the "Basic Shape" menu and scale it to 84 mm x 84 mm x 84 mm. You can also make it smaller or bigger, just scale it accordingly. I will show you how later on. If you would like to make a sphere with a higher resolution, go to this site. It is not necessary for the toy to work though.

Next we are are going to create the cylinder. Once again go to the "Basic Shapes" on the right-hand side. This time select "Cylinder". Scale it to a 32 mm diameter. The length doesn't really matter. Just select a value bigger than the diameter of your sphere.

Now we are going to alight the objects. Select both, by clicking on them while holding the shift key. Afterward, click on the symbol that I have highlighted in the third picture. Now you can click on the small circles that have appeared and that I have also highlighted in the pictures. Your cylinder should be placed in the middle of the sphere.

Then we are going to turn the cylinder into a hole. Simply click on it and select "Hole" in the top right corner (take a look at picture 4).

Hit ctrl + d to duplicate the cylinder. Click on it. A curved arrow will appear when you move your mouse over it, a wheel with different angles will be shown. Move your cylinder by 90°, duplicate it once again and turn it. Congratulations, this is all that is to it. Simply export the part by clicking on "Export" in the top right corner, as shown in the third picture.

Here you find the finished sphere on Tinkercad.

Next, we are going to create the parts that are piercing through the sphere. I decided to make them 3D printer-friendly and therefore didn't round the edges, but feel free to change the design should prefer the rounded look.

Once again start by creating a cylinder. Its dimension should be 30 mm in diameter and a height of 23 mm.

Next, select "Box" from the "Basic Shape" menu and scale it to 8 mm x 8 mm and a height of 50 mm.

Now we will create another cylinder. Its diameter should be 5 mm and it's height 9 mm. We have to place it on top of our box. So move it up by 50 mm by clicking on the small arrowhead and dragging it up. Align the pieces by selecting the small cylinder and the box while hitting "shift". Now you can center them. Simply select both pieces and hit "L". Then click on the small circles as shown in the third picture. Once you have oriented the pieces group them, by selecting both and hitting "ctrl + g" (you will know that the grouping worked when the pieces turn the same colour).

Create another cylinder with a diameter of 5 mm and a height of about 7.5 mm.

Since in my example, the diameter of the holes is h = 32 mm and the diameter of the sphere is D = 84 mm. L can be calculated with the following formula: L = - D + 2 · sqrt (D² - h²) = - 84 mm + 2 · sqrt ((84 mm)² - (32 mm)²) ≈ 77.6 mm.

We defined a = 23 mm and the thickness of the pole going through is p = 8 mm.

Therefore the distance holder needs to be slightly less than L/2 - p - a ≈ 7.8 mm. As I said above we are going to go with 7.5 mm.

Finally, we will have to orient the pieces. Move the box as well as the small cylinder you have just created up by 23 mm. Select everything and center the pieces (except for the height) as shown in the second picture.

Now we will have to move the pieces one last time. Move the cylinder to the back by -4 mm x -4 mm (half its dimension) and the small cylinder to the front by 2.5 mm x 2.5 mm (its radius). Simply export the piece. Congratulations, your second piece is done.

Here you find it on Tinkercad.

For the final piece, once again create a cylinder with a diameter of 30 m and a height of 23 mm. Like in the last step we are going to create a second, smaller cylinder with a diameter of 5 mm and a height of 7.5 mm. Move the smaller cylinder up by 23 mm and align the smaller cylinder to the middle of the bigger one. Now move it to the front by 2.5 mm x 2.5 mm. Group the two pieces.

Create another cylinder with a diameter of 5.4 mm (it has to be slightly bigger than your 5 mm cylinder that sits on top of the box from the last step) and a height of 10.2 mm.

Move it up by 13.8 mm (23 mm (the height of the bigger cylinder) - 9,2 mm (slightly more than the length of the cylinder that sits on the top of the box)). Center the piece with the grouped pieces you have created before. Move it to the back by -4 mm x -4 mm and turn it into a hole like we have done before with the cylinders going through the sphere.

Export the piece and your third part is done. You will have to print the second and the third piece three times and your sphere once.

A word of caution should you want to print the toy for a baby. They will definitely put them into their mouth. While toys are made from ABS and PLA is considered food-safe, 3D printer filament usually contains additives. Printing something that is food safe and therefore entirely safe for a baby is tricky. Here is a great article on the subject. I suggest you read about it and decide for yourself. Like I said before this toy is also great for older kids and adults who like to fidget.

Here you can find the finished piece on Tinkercad.

Since the assembly is a bit tricky to photograph I decided to use digital images and make the sphere seethrough.

Start by gluing two of the pieces you have designed in the last steps together as shown in the first picture. Next put them into the sphere as shown in the second picture.

Put your next piece that has the box sitting on top into the sphere as shown in the picture and glue one of the smaller pieces onto it. Don't assemble the pieces outside of your sphere, since you won't be able to get them into it later on.

Last you will have to push the last piece with the box on top of it the sphere and glue the small piece on top of it.

Congratulations, you're done, have fun playing with it.

After my 3D printed prototype worked really well I decided to make the toy out of wood, since I am currently obsessed with wood turning.

What you need
Material

• a piece of lumber (about 10 cm x 10 cm x 15 cm )
• a piece of lumber (about 4 cm x 4 cm x 20 cm
• a small round rod (diameter: 5 mm; length: about 5 cm)
• a small rod with corners (about 8 mm x 8 mm (I could only find one with 10 mm x 10 mm and didn't want to cut it on my table saw, so I used it as it was; lenght about 20 cm)
• a beer coaster
• For the drilling jig:
  • two pieces of lumber (about 15 cm x 15 cm and a thinckness of about 4 cm)
  • five M6 flat head screws (70 mm)
  • five M6 nuts
• optional: glaze or baby safe paint

Tools

• a lathe
• a drill press
• 30 mm forstner drill bit as well as an extension so that you are able to drill 84 mm deep
• For the drilling jig: two pieces of lumber (about 15 cm x 15 cm and a thinckness of about 4 cm)five M6 screws (70 mm)five M6 nuts
  a 40 mm forstner drill bit
• a ruler
• a vernier calliper
• chucks to mount the wood
• a spindle roughing gouge
• a spindle gouge
• a parting tool
• a pencil
• a compass
• clamps
• a thin saw
• For the drilling jig:
  • a 38 mm forstner drill bit
  • a 7 mm drill bit
  • a tension belt

If you own a sphere turning jig, you probably know how to use it, so I am not going to explain it here. Instead, I am going to show you how to turn a sphere by hand. Start by mounting your piece between the centers. Your piece of wood should be about 2-3 cm (~0.8 inch to 1.2 inch) longer than the diameter of the sphere you would like to turn. Turn the block to a cylinder of 84 mm (~ 3.3 inch) diameter. You can of course choose an other diameter, but you will have to adjust the measurements accordingly. Draw a line around it in the middle. This is going to be the centerline of the sphere. As you can see my line was not in thecenter. This was because there were a few cracks on the right side of my wood and I didn't want them to be in my sphere. Draw two more lines on either side of your center line at a distance of 42 mm. Use a parting tool to turn down the outer edges to about 25 mm (1 inch). Then use a gouge to clean down the sides as shown in the fourth picture.

A well-known trick to turn a sphere is to use a beer coaster. Hold it to one side of the sphere and use a pencil to transfer the diameter onto it. Afterward use scissors to roughly cut out the form. Make sure to stay inside of the line as shown in the second picture.

Then hold it onto the cylinder and turn on your lathe. It will remove the excess paper and leave you with a perfect sphere. Make sure not to use the centerline, because you will be left with a slight burn mark on the wood.

Now we are going to finish the sphere. Use your spindle gouge to carefully turn the cylinder to a ball shape. Constantly stop the lathe and control your process with the beer coaster.

The ends need to be smaller than 32 mm, since this is going to be the size of the hole that we are goint to cut into it. Once you are done, use a saw to cut the sphere off.

Usually you would have to remount the sphere to finish the form, but since we are goint to cut holes into it, there is no need to do this.

I have seen people just cut a hole into a board, place the sphere into it and use the drill press to drill into it, but I was afraid that the sphere might slip. Therefore I decided to make a hole cutting jig.

The construction is quite simple. I used two about 15 cm x 15 cm x 4 cm pieces of wood mounted them between the centers and turned them to a cylinder with a diameter of about 14 cm. On both sides of the cylinder, I created a tenon so that I could mount them into a four jaw chuck.

Once you have created your cylinder with the tenons, mount it into your four jaw chuck and drill a 38 mm hole into the center to about half the depth. Turn the piece around, remount it, and drill a hole from the other side through the middle. Next, hollow it out. It doesn't need to fit your sphere perfectly. It is mainly just to prevent dents.

Repeat the process with the second cylinder.

While still on the lathe mark a circle as shown in the third picture about 1 cm from the sides. Measure it.

The circumference is calculated with c = D · π. "D" is the diameter.

So if its diameter is 13 cm the circumference is about 47.12 cm. Divide your result by five (since we are using five screws). This is the arc length in this case it is about b =9.42 cm.

Now you have to calculate the chord length with s = D·sin(b/D)

Make sure that your calculator is set to radiant. In our case, the chord length is about 8,8 cm. Set your compass to 8.8 cm and mark where you have to drill as shown in the third picture.

I secured the two pieces together with a tension belt and drilled through both at the same time. I later decided that I wanted the screw head to be flush and therefore drilled bigger holes ontop. I should have done this before drilling all the way through since it was hard to find the center.

Next, we are finally going to drill the holes into the sphere. Mount it into your jig and use you 32 mm Forstner bit to drill all the way through.

Now we are going to mark the other holes that need to be drilled. Start by finding the middle between the two openings of the hole you have drilled.

Since the diameter of your sphere is 84 mm the circumference is about 263.89 mm. Divide it by four (two holes with two openings) and once again calculate the chord length with s = D·sin(b/D). It is about 49.4 mm. So set your compass to this length and mark the center of the holes as shown in the second picture.

Draw 38 mm circles around the centers, which is also shown in the second picture. Now you should be able to precisely mount your sphere and drill the holes.

Noe we are going to make the plugs. They should look like the ones in the pictures. You can use your beer coaster to check the curvature, should you want it to be the same as your sphere.

The length of each plug is 23 mm. Measured without the curvature. The diameter should fit your holes, so about 30-31 m. You can test fit them with your spherewhile still on the lathe.

Now we are going to drill the holes into the plugs. Finding the center of a cylinder is quite easy. Simply draw a line, find its center, and draw a line perpendicular to it. The center of the second line is the center of your circle.

Drill a hole with a diameter of 5 mm at a distance of about 5 mm from the center. The depth should be 10 mm. Next to it drill a 10 mm hole at a distance of about 14.2 mm (sqrt((10 mm)²+(10 mm)²)). The depth should also be about 10 mm.

Cut the round pole to six pieces with a length of 15.5 mm and glue them into the smaller holes in the plugs. I had nothing to mount the edged pole to my lathe. Therefore I rounded the ends with a Dremel. You will need three of them.

The part with the corners should be 5 cm long. The rounded part has to be slightly less than 1 cm.

Glue the poles you just created into the bigger holes of three of the plugs.

As you can see in the picture I added some color to the wood since I knew that my son would prefer colorful pieces. Make sure to use paint or like in my case glaze that is approved for baby toys. I used glaze since I wanted it to still look like wood.

As I have written in step 6, the assembly is a bit hard to photograph. Take a look at step 6 to see digital images of the assembly.

I suggest to try to fit the pieces without glue first to make sure everything works and has the right measurements.

Simply use glue to hold the pieces together. Congratulations, you are done. Have fun fidgeting.