Hedgehog LED Night Light

My daughter has a friend who wanted a hedgehog for her birthday, but her parents said no. That friend was sad because she had her heart set on a cute hedgehog so I told my daughter that we could give her one.

As a parent myself I am not one to go against another parent’s decision, so I never intended to give her the real deal. A quick search of Thingiverse and I found exactly what I was looking, and I didn't even having to “fix” or alter the files. “bs3” had already done the work for me by designing a “Lovely Hedgehog” and posting it to Thingiverse. I used file “hedgehog_A_hole”. (For the record bs3 named the file; I did not.) The inside of the hedgehog is hollowed out for a light to shine through. BS3 made both a tall version and a short version of a solid and a hollowed out hedgehog.

The original hedgehog gift was made and given two years back. This month a family friend is having a 40th birthday party and I have nothing to give so I am making another hedgehog for a party. I have all the parts on hand and this build is super simple. Even more so if you own a 3D printer. I will try to call out where you can get all the parts and share the files for the box. I am not sharing bs3's hedgehogs files as they are already available for download on Thingiverse.

Tools needed for this build include:

3D printer. I use an original Dremel Idea Builder.

Filament – PLA, I used dark blue for the box and translucent for the hedgehog.

Soldering iron

Wire cutter/stripper

Glue – Super glue, 5-minute epoxy, and Hot glue

Hot glue gun

Parts Needed:

Switch – Sparkfun COM-08837 or comparable. The box was designed for this switch.

3D printed box & bottom cover

Printed Hedgehog in transparent PLA filament

Wire

Solder

Flux

Diffused white LED 10mm – Sparkfun COM-11121

Battery Holder – I printed mine

Two AA batteries wired in series

Safety:

This is a mostly safe and simple build that does not take much time to complete. Do not breath 3D printer fumes or soldering fumes. Be careful not to burn yourself with the soldering iron or the hot glue gun. Other than that I do not see much that could harm you when working on this project.

The hard part of the design work was done by someone else and offered up on Thingiverse. Thank you BS3, and well done on the Lovely Hedgehog files. I took the size of the hedgehog and used it to decide what size box I wanted to house the batteries and the switch. All components fit nicely into the box without force, but there is not a lot of extra room.

I printed a simple box with a hole in the top to pass the LED light through which places it into the open body of the hedgehog. I made a hole in the back of the box to hold the switch which was purchased from Sparkfun. Most any on-off switch will do; this just happens to be a switch I have on hand.

I printed a couple of AA battery holders that were also found on Thingiverse. Thank you, Chris_E for your AA Battery Holder. I have made my own several times, but I do favor the simplicity and effectiveness of this design. Although I may extend the length of the print by 2mm next time as it is a little tight with the gauge of wire that I am using for this project.

I added a photo above of the very simple circuit for this build. It is simply made up of two batteries in series that are wired to a switch and then an LED bulb. It is so simple to build and only a few joints to solder. I soldered the wires to the switch and to the LED and that is it. The battery connections are simply glued in place. (See photos for an illustration of this and comments)

Here is a link to the box and bottom cover files on Tinkercad. https://www.tinkercad.com/things/gBRPHnHQLzm-powerful-duup/edit?sharecode=i_N29dtAQyUJ9YT-UREgKADpmWJT35EPeOpZE7lfdjE=

The first step is to solder the wires to the switch and pass them through the hole thus locking the switch into place with its tabs. One wire should run from the switch to the plus side of the LED bulb and the other wire from the switch goes to the plus side of the battery box that we built by gluing the battery holders back to back. Then solder a wire from the negative lead of the LED bulb to the negative side of the battery holder.

Center and glue the Hedgehog to the middle of the top of the box that you printed or had printed for you by a service or friend. Place the LED up into the hole to the level that it best illuminates the hedgehog. Hot glue your wires and LED to the box as needed. I ended up using a different LED than the one I designed the box for so I drilled out the hole a little bit larger to pass the LED through. I thought this to be easier than trying to fight soldering everything together with only the LED leads passing through the hole. This way I could easily see wee what I was doing and could easily clamp the wires to the leads to hold them in place while soldering. After assemble I could then push everything up into place.

Test your circuit to make sure everything works. If all looks good and it should, then add drops of hot glue to the corners of the bottom cover and push it onto the bottom of the box. This will hold everything in place, but still allow you to open the box later to change the batteries as needed. I did tighten the bottom lid design up just a bit so it does fit tight enough now that you could skip the glue and just press it on.

I know that this is a very simple idea. I have now made a two of these hedgehogs. I have also made a Baymax from Big Hero 6 night light in a similar build.

In case you hadn’t thought of this before I wanted to share this way of making glow in the dark characters for others to enjoy.

Total print time is around 6 hours for the battery holders, hedgehog, and the box.

Total cost is most likely around $3 to $4 USD for filament, switch, wire, and LED bulb. This of course if you own a 3D printer. If you do not have access to a printer, then I believe it is around $5 an hour for someone else to 3D print for you.

Total assembly time is under a half hour for soldering and gluing. Unless you paint your parts as I did here, then it takes about an hour of assembly and finish time. Not including dry time. I painted my parts in an epoxy called XTC-3D, which is a favorite finish of mine for printed parts. It is a paint on epoxy that fills in print lines quite nicely.

If you like this Instructable you might want to check out another one I wrote using the same concept with a silhouette instead of a statuette. It is called Halloween LED Light Boxes. https://www.instructables.com/id/Halloween-LED-Light-Boxes/

I am always open to questions, comments and constructive input.