This post is a “Making Of” of a light- and nightfury plush toy – inspired by the “How to Train Your Dragon” animated film series – including battery powered glowing eyes, all build by people that did not have any experience in making stuff with electronics at all.

Maybe it all got a bit out of hand…

Note — We’ve put some links to the equipment and material we’ve used in the process. The links are just there to make it easier for the readers to find them – there are no referral or affiliate links!

Getting the Idea

So, let’s start with how we got there.

In 2018 we – that’s Yaybird and nobbs – were both at the Chaos Computer Club’s 35C3 congress for the first time and, to be honest, we were simply overwhelmed by all the impressions. Especially the assembly areas, all full of people soldering, making and building fancy stuff – and blinking lights all over the place. So we decided: “We want to build something fancy, too!”

But what exactly could we build? The only experience we both had with making stuff was sewing plush toys – to be more precisely, Yaybird had some years of experience, nobbs not so much. That’s all we had.

But chance came to our aid in finding the idea for our first project! We go to the cinema - quite frequently. And all of a sudden a certain film popped up in our watch list: How to Train Your Dragon – The Hidden World.

Yaybird remembered that she had a sewing pattern for a nightfury lying around somewhere. While she usually creates her own patterns when sewing plush toys (aka plushies), she once saw a pattern and was curious how it would be to sew a plushie with the pattern of someone else – so she saved it “for later”. Luckily, we were able to find it again – more on that, later on.

Okay, so we decided to make a nightfury plushie… but how to add some electronics to make it fancier? How to integrate lights into the stuffed toy? Naturally, they shouldn’t just light the plushie up, they should make sense in a certain way, fit the nightfury’s look. Yeah, we know – a lightfury lightens up his/her body before breathing fire, but keep in mind: it was our very first project working with electric components, so we tried not to overdo it, keep it simple and decided to do glowing eyes.

But First, Some Practice!

We both were more than sure that we had no soldering skill at all – haven’t held a soldering iron in our hands our whole lives. Obviously, we didn’t own one. So we did some research and bought some basic equipment:

• a soldering station, some generic “ZD-931” model made in china
• a helping hand tool
• some generic soldering wire, heat-shrink tubing
• and most important, the “Lernpaket Conrad Components Basic Löten lernen”, a kid-friendly starter kit to learn soldering

Well – and then we started practising. First, following the instructions of the starter kit, followed by watching tons of videos and making first uncertain soldering tries. And mistakes, lots of mistakes, e.g. trying to desolder an annular ring and in the process burning of the contact – rookie mistake.

Some Preparation

Like mentioned above, Yaybird never used a sewing pattern of someone else. Having found the pattern again – made by the super talented Choly Knight – she decided to modify it a little and use that as a base for the project. The pattern is super easy to follow and turns out perfectly cute – you can find it here!

At this point we also decided, regardless of how well the nightfury ends up looking, we’ll also do a lightfury version! Some more modifications to the sewing pattern and off we went.

Let’s continue with the materials for both the plushies and the equipment that was required in the making.

For the Fluffy Parts

The combined material list for the night- and the lightfury was the following.

• the sewing pattern, printed on paper and cut out
• 50x100 cm² white and dark blue or black minky fabric¹
• another little piece (~ 10x15 cm²?) of red minky fabric
• fibrefill, we’ve got this one
• an approximately 30x30 cm² piece of cotton fabric
• a white and a dark blue / black , ~12-15 cm long (we’ve this crazy stuff as stock…)
• generic white and dark blue / black yarn
• and finally a sewing machine – not required, but makes your world a loooooot easier!

For the Electronic Stuff

As the electronic components are the same for both, we used the following set of materials for each of them.

• Arduino Nano to control the lights
• a small USB Powerbank to power it
• a micro to mini USB adapter as the ports weren’t compatible
• one electrolytic capacitor, 1000µF
• two LEDs of a NeoPixel strip
• a 470 Ohm resistor
• some other generic stuff, e.g. wires, heat-shrink tubing, electrical tape

For the Eyes

• some transparent white polymer clay; we chose translucent white Fimo – one block was more than enough for both plushies
• black acrylic paint

For Holding It All Together

• hot glue, lots of hot glue!

Let’s Get Real

Since Choly Knight explains perfectly how to put together all of the pieces of the sewing pattern, we are not going into detail. So we’ll just explain the adjustments we made to securely integrate the electronics into the plushie – aka we made an inner pocket with a zipper on the side of the lower body.

The pocket is approximately 10x10 cm², just enough to fit the Arduino Nano and the powerbank and should have an opening towards the head which is necessary to route the wires to the eyes. The tricky thing here is, that the zipper needs to be attached to the cotton fabric, used as the inner lining, and the minky fabric. Again, no detailed instructions – a great tutorial with tons of pictures how to attach a zipper to two pieces of fabric can be found here.

That was the major change we made to the pattern.. For the lightfury we adjusted the shape of the tail and added fewer bits to the head. We also used the opening in the head – used for stuffing – to route the cables from the body to the eyes.

The Eyes

The eyes are made of translucent polymer clay so the light can shine through them. We knead and rolled out some of the clay and cut out the shape of the eyes. To make it easier to attach the LEDs we added some clay rolls to the back of each eye to later fixate the lights. Finally, we then bend the eyes to a slightly curved shape and baked them according to instructions.

Electronics

So, no previous experience with the Arduino Nano and the NeoPixel LEDs meant a lot of research before getting practical.

Providing Power

After some google-fu it quickly became clear that a regular powerbank plugged into the Mini-B USB port of the Arduino would be enough for the Nano but also two NeoPixels. The powerbank we used has an electrical charge of 2500 mAh and an output of up to 2.1 A at 5 V.

Roughly estimating the power consumption of the Arduino Nano – approx. 20 mA (cf. the official tech specs) – and two NeoPixels (max. of 60 mA each at full brightness). So, a total of approx. 140 mA at full brightness white light – a setting we didn’t plan to use. Assuming a power consumption in the ballpark of 100 mA seems reasonable – and results in a battery life in the range of a full day; more than enough for a plush toy!

This also made the wiring easier, as the first of the two NeoPixels only has to be connected to a 5 V out and a ground pin of the Nano. The second NeoPixel then is connected to the first one – quite easy to do, see the “creepy” picture above.

Things to Watch Out For

Adafruit luckily provides a collection of best-practices for use of the NeoPixels. These especially tell one to:

1. put a 1000 µF capacitor across the plus and minus terminals of the power source used for the LEDs – prevents sudden changes in current drawn by the LEDs,
2. place a 300 to 500 Ohm resistor between Arduino data output and the first NeoPixel’s data input.
3. other things to consider – not that important for this project.

Assembly

Putting all the previous considerations together and deciding to use pin D6 of the Nano as the data out for the NeoPixels, the resulting complete setup looks like this.

Since we couldn’t foresee how the whole thing would end up – wires, heat-shrink tubing and electrical tape were used quite generously. In the end, everything played out fine!

Code

Last thing missing for the electronics? Right, the programming. Since we just wanted some simple color fluctuations in a narrow hue of blue / green and a simple blinking effect, the code isn’t very complicated – to be honest, it’s also not that good, but it works.

As this was also the first time working with the NeoPixels, we utilized the FastLED library to make development as painless as possible.

The current version is hosted as a gist, but may get a revamp and it’s own repository… time will tell.

Putting It All Together

Not much left to do, if you’ve followed along so far.

Once the electronic components were done, we threaded the NeoPixel eyes through the sewn in pocket’s opening into the body and towards the head, cf. again the “creepy” picture above. Further threading them into the head – positioning everything for the final steps.

Next: gluing the NeoPixels onto the polymer clay eyes and then gluing the eyes to the head – with a lot of hot glue. Really, there’s never too much hot glue – as long as you can’t see it, everything’s fine!

Last things to do: sewing up the head, attaching it to the body, attaching extremities if not already done, painting the eyes … and that’s it!