Step 4: Wrap the Assembly
Take about 2" of tape, and wrap it around the entire assembly. Pull it tightly over the end of the negative wire, until the middle of the wire no longer makes contact with the magnet and the LED stays off.
If the LED is not going off, try repositioning the magnet, or making the platform slightly thicker by adding a layer of tape. Also the space between the wires could be too little, so try adjusting the bend so that there is enough space for the wire to hang over the magnet without touching it. It may seem tricky at first, but after you get it once you'll get all of them correct right away from then on, without any adjusting needed.
That's it! Make a bunch, and go out and have a throwie party! Throw them at anything magnetic, and they should turn on as soon as they stick! Also useful as a pinch-on LED flashlight!
Disclaimer: The original design is not mine; this is just my modification of it. I take no responsibility for what you do with these.