For Halloween, my son told me that he wanted to be a dragon. What kind? I asked.

A fire breathing one.

Since small children with flamethrowers are generally frowned upon, he settled for sound reactive lights.

I am a busy person, so whatever shortcuts could be thrown at this costume, got thrown at them. First off, black trousers, red sweatshirt, base done. Secondly twitter informed me that articulated dragon wings are a Thing on the internet, so a set of those got purchased pretty sharpish. Luckily Child does not like having anything on his face, whether that be makeup or masks, so it was down to whatever I could figure out to whack on over the sweatshirt.

The design appeared, scribbled by me while Child looked on and corrected me. Frequently.

And this is how we ended up with this implausibly detailed design.

The idea is that there’s an Adafruit Circuit Playground Express on the chest, set to detect sounds, and then fire off er, fire-coloured lights over the front of the costume. The other part is that he wanted to actually code the lights, so I was limited to the microcontrollers he had experience of – it was that or the Micro:bit.

The lovely thing about the Circuit Playground is that you can code it at least three ways – MakeCode, Circuit Python, and that other thing. You know, that one.

More on that later.

As I’m sure everyone does, I wrapped half of Child in chip paper (Americans, it’s the outer layer of what fish and chips is wrapped in. The inner layer is too greasy.) and drew where the chest plate should go. The shoulder plates were fashioned out of the recycling (cereal packets) and tested for flexibility.

Then I marked the pieces out onto the back of some red glitter felt, cut them out and hit a snag. I wanted to pin the shoulder plates together with paper fasteners, but we didn’t have any, so I improvised. Turns out bent paperclips work just fine.

Chest plate next.

We did a lot of umming and aahing at this point, as the glittery red didn’t contrast very well with the sweatshirt. I focused on the positioning of the Circuit Playground and the lights while that got mulled over.

I cut a diamond/rhombus shape out of mdf, with a hole for the Circuit Playground to fit in snugly, before realising that wires are a fairly important part of the setup. Cue a bit of filing.

I gave the MDF a coat of primer, and set an orange perspex diffuser into the hole, and tested this out with the pumpkin candle tutorial from Adafruit to see how it looked. Pretty good, I thought.

There was a problem though. The diffuser meant that the microphone/sound sensor on the board wasn’t picking up enough of a difference between a moving child with rustling clothes, and a roaring child who was pretending to be a dragon. All sorts of misfires (pardon the pun) meant a redesign.

And then… into my life appeared this AMAZING dragon scale material. Couldn’t not use it, as it was both scaly and black (and thusly contrasted with the sweatshirt perfectly).

Enter the next three nights of my life, soldering these little things onto snippets of wire to fit on the pattern I’d drawn. Layouts are very important so that you don’t end up with too short a join, or an impossible bridge.

Exactly why I sat down and drew it first, before cutting all those little bits of wire. Sadly, my brain hadn’t registered that I was looking at the inside of the chest plate, and that the Circuit Playground would be facing outwards. [insert facepalm here]

Note the complete flip of the pins. D’oh!

I still hadn’t noticed, so I commenced snipping the wires to the right length and then soldering them at the right angles. I was feeling quite smug at this point.

And now all I had to do was fit the Circuit Playground onto the wired LED chest plate and… oh. I think I stopped taking photos at this point as I frantically rewired the start of each strand to the correct side of things, so as a consolation prize here’s a very ugly photo of my idea of securing wiring to the back of something where you know no one will see it.

We used MakeCode to add the lights in three sections, so that we could control them in a ripple effect (marked sections 0, 1 and 2 on the paper).

On the front, I used stick on gems as diffusers for the pixels. Surprisingly, we only lost one gem while out trick or treating!

And finally, it’s ugly and quick but it works, we duck taped the chest plate on (the wings covered it), popped the wings over the top and bada bing bada boom – one baby dragon! When he roared, the lights lit up from bottom to top in a kind of ripple effect, and as you can see in the last photo, it was enough to light the way for him and his friends when trick or treating.