Make a LED Papercraft Soldering Unicorn

For the CRASH Space booth at Open Sauce this year (and then Orange County Maker Faire, and then Bay Area Maker Faire), I designed a papercraft version of our mascot Sparkles, the soldering unicorn, and ran 300 copies of various colored designs on our Riso machine. It includes a circuit with a color-changing LED and you can wear it as a finger puppet. It takes about 15-20 minutes to assemble. There are written instructions below, or you can watch the assembly video to make your own!

1. Printout of either the plain or colored pattern, ideally on cardstock
2. Make sure to print at 100%. The images on the front and back should be aligned.
3. Scissors
4. Copper tape, 1/4 inch
5. Color changing LED (single color is fine if you're allergic to fun)
6. 2032 coin cell battery
7. Scotch tape
8. Tape runner (preferred) or double sided tape

Cut out the three pieces on the solid lines. Don't miss the solid lines on each that go in from the outside of the shape, including the slot on the unicorn's forehead.

Add copper tape to the two indicated locations. I recommend peeling only a little bit at a time and applying it to strips of steps 2 and 3. Be careful when applying. If the copper tape tears, your circuit will not work and you'll need to use a new piece.

Fold up the soldering horn as indicated on the model (fold step 4 piece down, then continue for 5 and 6), it will become one flat roll. Tape it in place ON THE INSIDE (this is where the tape runner starts to show how awesome it is). Do not put tape around the outside (yet).

Squeeze the edges of the end and insert an LED with one leg in contact with the copper tape inside and one leg in contact with the copper tape on the outside.

(I like testing the circuit at this point, since it's much harder to fix it later. To test, touch a coin cell battery with one side touching each of the copper tape strips. Flip it over and/or squeeze where the LED legs are if it doesn't work.)

Once you've tested and know that the placement works, a piece of clear tape around the outside will hold things in place nicely.

Attach the battery holder piece to the unicorn head piece at spot A (see photos for alignment).

Flip over the unicorn head so that the outside (instructionless) side is up. Take a look at the three strips on your soldering horn piece. You need to slide the longest and shortest strips into the slot, leaving the middle one on the outside. Refer to the photos or video to see which direction it should be facing.

Double-sided tape or use a tape runner to attach the short strip to the inside of the forehead where indicated, and the long strip going the other direction. Fold over the extra on the other side and secure it. The end needs to be secured from the back in the spot where the battery will go.

DO NOT cover the copper tape inside the battery compartment (i.e. after you’ve folded it over) or your soldercorn will not work.

Follow the instructions on the pattern for folding over the flap for 12 (no tape), taping down for step 13 and 14.

Time to give it shape! Adhere the tabs to the inside of the soldercorn’s jaw where shown (grey boxes) to form the face. Check the pictures or video for help with this step.

Step 16 is where you form the back of the unicorn's head. Add double sided tape and then bend it down so that it has just enough space for you to insert your finger.

Bend up the unicorn horn to where it should be. Insert a 2032 coin cell battery into the compartment and slide the outside copper tape strip behind the battery. If it doesn’t work, try the battery the other direction. You also might need to squeeze the legs of the LED and/or battery compartment to secure the connections.

The strip that you just put in is your switch. It doesn't get taped down. You can pull it out of the battery compartment to turn off your soldercorn and save battery.

The long pieces at the back of the head are the hair. Curl the hair around a cylinder like a pencil, fold it into kinky curls, or leave it as a mohawk if you’d like.

Place your puppet on your finger, and play to your heart’s content!