It's a good idea to plan out where you want the unicorn horn to be. Since I'm doing it on my hoodie, I'm placing it near the lower brim of the hoodie, in the center. Then, I used an X-acto blade to score the spot where I want the LED to be. Once it was marked out, I then dug into the fabric, effectively poking a hole.
Once I had my hole in the hoodie, I proceeded to insert the LED from the inside of the hoodie and pull it out through the fabric so the LED went through the other side.
Then, I could install the LED holder piece by pressing the LED into it. Really easy, it just press fits into place.
With the LED installed into the holder, I proceeded to place it back onto the hoodie, so it's flush with the fabric. Then, place the 3D printed unicorn horn over the LED holder. I recommend orienting the horn so the tabs are away from any seam – that could potentially make it harder to poke a needle through.
Needle & Thread
Now it's onto sewing! It's totally not duanting, if you can solder wire, you can totally sew! Start by picking out a fairely thin needle (if you're attching the horn to a hat, the thinner the better) and some thread – Ideally a color that matches your headware (here it's black, obviously ;-). Choose a decent length of thread, just make sure it's not too long or short. Then, thread through the eye of the needle and tie the two ends of the thread together so the eye of the needle will be in the middle of the thread.
Now it's time to sew! I started by poking the needle through the inside of the hoodie and coming up through one of the sew tabs. Then, poke back down on the outside perimeter of the tab and thread until a tight loop is made, holding the sew tab down to the fabric. Then, create a few knots and tighten.
Use a pair of scissors to snip off the excess thread – fight the urge to use your teeth and byte off the thread ;-)
Repeat this process for all for tabs! If you get stuck, not a problem! Just snip off any thread and try again. You'll get better with practice anyway! I was able to get away with a single loop for each tab – but obviously the more you add, the more secure the horn will be!
Since my wires were a bit lengthy, I ended up adding loops to the wires to keep them in line, preventing them from going all over the place. Just a few regular loops to guide the wires down to the back of the hoodie, near the tag.
Speaking of the tag, that's actually where a good spot if to store the battery and JST switch breakout. There was a large patch right above the tag – I made a slit there and turned it into a little store pocket but if you don't have one, you could just secure it to the tag.
Welp, we're just about done. Now we can turn the switch on and see our sewed LED horn light up. All that's left to do that this point is to wear it out! Congrats, you're now a magic unicorn! :-D I hope you learned a lot while making this project and enjoyed building it. If you built one, PLEASE take a picture and share it with us on Twitter, Instagram or even post a make on Thingiverse. We'd love to share it to the world!