Sonic the Hedgehog Costume

My son loves the Sonic the Hedgehog movies and without hesitation asked us for a Sonic costume for Halloween this year. My wife and went online and did some searching, there were some very expensive ones that looked great and some "ok" ones that were more reasonably priced. But, I thought that was not good enough if we were getting the "ok" option I needed to make it better. To be fair I would have done something to spruce up any suit, but I feel safer when it's an option I can repurchase if I mess up.

Sonic the hedgehog costume: Costume 1 and Costume 2

Arduino Nano v3

Resistors

Felt

PCB proto-board

Wires (lots of wires)

WS2812B LED strip

3 screw 3.5mm sterio audio/video male female connectors

So to start off we needed to find a good costume which I could modify in some way. My goal was to try to create a look that mirrored the "powered up" Sonic from the movie where he glowed. Two things to consider, a costume that could handle all of the electronics and how to make the lights penetrate the felt but still look interesting. We bought Costume 1 and thought it would fit my son, however it was small (even thought we bought the large). The head piece fit well and had space inside of the "quills" to fit some LEDs. We decided to keep it temporarily and order Costume 2 to see if it was a better fit. In the end the costume body fit much better, however the head piece was not usable as it was a single piece of felt and there was no space to fit things inside of it. So we kept both and decided to mix and match, the head from Costume 1 and the body for Costume 2.

I started out by just holding the LEDs against the felt to see how much light would get through. The LED light easily penetrated but was too focused, a diffuser would be needed. So my wife was kind enough to use her sewing skills to open up the head so I could try fitting different diffusers into it. She cut open the lining and then used a seam ripper to open the seams for the "quills" in the head. I tested a handful of different diffuser designs, but settled on a quick and dirty one that I made in Tinkercad. I printed it out using white PETG and a mirrored image. There is a nice groove near the edge which allows for the LED strip to fit in. I taped the two pieces together with a test strip inside and slide it into one of the quills. I attached the strip to the arduino and tested it out. The first 3D printed diffuser was too large to I scaled it down to about 80% and printed out a total of six sets.

I designed out a basic concept for how the connections would work. I breadboarded the entire setup to make sure the design worked. To make it easier on myself some of the wires were attached to 3.5mm audio/video screwable connectors. This allowed me to disassemble everything or test a single component much more easily. It's a lot of cables but this is mostly because each LED strip needs three wires and I also had them going to a resistor just so I didn't burn them out.

To make it easier for someone to replicate this design I have attached a photo and fritzing file of my electrical design. I also attached the arduino file to run everything.

Once I had the design all figured out and tested I replicated it on a PCB board. The LED strips in the head was soldered directly to the PCB board as they weren't going to have issues when putting on the costume. The LED strips meant for the body weren't added at this point but the power and data wires were soldered to the board to be added later in the process. This took a while as I went slowly and tested each connection individually to make sure each quill worked. The buttons were connected using the 3.5mm audio/video connector.

For the buttons I used tactile switches which I hot glued to a glove my son would wear. This appeared to work at first, but as we would learn later it would need to be re-thought through.

Once I had the head assembled I kindly asked my wife to wear it so I could test it out and get a video.

I am able to power the entire system using the USB plug on the Arduino Nano off of a USB battery pack.

A week before Halloween we did a dry run of the costume at a Trunk or Treat event. The system overall performed admirably, but like any test it also showed some areas of improvement.

I initially attempted to have contact switches as the controllers and hot glue them to a glove. We abandoned that idea after a dry run which resulted in a broken contact on one of the buttons. Instead i made a quick and dirty handheld controller with two buttons. This ended up being much better and a very easy swap out as I just replaced the buttons and ran use the same wires and connectors as before.

I still needed to figure out how to make the body strips diffused and still work out. I knew my son would not like them to be right on him, so after consulting with my wife she suggested putting them into some felt sleeves. She cut several strips longer than the strips and wires. After hot glueing the wires in place and then hot glued the strips closed around the strips. The white felt diffused the light very well and allowed us to pin the strips within the body so they wouldn't float around too much (something I initially forgot to do on Halloween).

Another major adjustment was my miscalculation on the weight of everything in the head. This is primarily due to the 3D printed diffuser sleeves, which could have been designed to be much lighter. They unfortunately pulled the entire setup back off of his head after he walked around. To fix this my wife actually cannibalize the front of the headpiece from the second purchased costume. She cut the front off and sewed it to the front of the head piece we were using. This allowed the entire setup to stay on his head by having a little bit of a bigger lip on my son's forehead.

The result was a pretty awesome costume that my son loved. There is a major advantage to having your kid covered in LEDs, you can see him as he trick-or-treats and you don't have to worry about cars not seeing him. The costume survived the night and is still functional to be used at a later date if desired.