In this instructable, I'll show you how to make a charming three-dimensional broach in the shape of a heart, lit from the inside by an LED. If broaches aren't your thing, you can also take the heart and put it on a card, on the top of a gift box, on a necklace, or in many other useful locations. A handy magnetic attachment system lets you snap it on and off with ease.

I don't have a 3D printer but I wanted to have a go at constructive plastic fabricating. And, since my brother doesn't have girlfriend (and probably wouldn't want one), I thought someone should make him something nice for valentines day -- a 3D glowing heart, for example.

The heart is is made from (carefully) extruded hot glue, and it has a SMC LED powered by a CR2032. I was going to use a normal broach pin, but I have had some painful encounters with that species so I decided to use a small Neodymium magnet. Conveniently, the magnet also acts as a switch, clamping the power wire onto the battery.

This is my entry for the Valentines Day contest, so if you like it please Vote!

Step 1:

Materials, tools, and supplies:

Glue sticks (1~2)
1 CR2032 (I got mine on ebay, $4 for 100 +$5 for shipping to Canada, a total of $10.15 for 100)
1 SMC red LED
1 tiny (super flat) neodymium magnet
1 medium size (1/2" by 1/8~1/16th" approx) neodymium magnet
1 small piece of wire

Soldering iron
Solder
Glue gun

Cool, smooth surface for the extruding platform (I used a computer power supply case)
Oil (1 teaspoon)

Optional:
Helping hands soldering helper
Water in a squirt bottle (for cooling)

Step 2: Oil the Platform

Spread a VERY thin coating of oil on your printing platform. This will prevent the piece from sticking.

Step 3: Layer, Cool, Layer, Cool, Repeat!

Now the fun begins! Carefully build up the heart layer by layer, working from the edge in, making the bead as even as possible. It probably won't look that nice at first, but don't worry, we will smooth it out later.

If you're feeling impatient you can squirt it with water to cool it faster, as it will take 20~30+ layers to finish. I started by making a smaller heart, and then adding another layer of layers, which made it much smoother and big enough to hide the CR2032.

Step 4: Smoothing and Final Touches

When the layering is done and it is big enough and tolerably smooth and shapely, it is time for the final smoothing. For this, use the side of the glue gun nib to melt and smooth the outside. If it isn't quite symmetrical, use a hobby knife to shape it.

Now the Heart is done. Time for the electronics!

Step 5: Solder and Embed the LED

Cut a 1 1/2" piece of wire. Strip both ends, and solder it onto the positive terminal of the LED. Cut another piece about 1" long. Strip one end normally, and the other longer so there's about 3/8" of bare wire exposed. Solder the short end onto the LED's negative terminal.

Embed the LED in the heart by melting a small hole with the glue gun. Tape the extra long bare section of the negative wire to the CR2032, then glue the electrical tape to the heart to secure the battery.

Step 6: Wear It!

Stick the smaller magnet to the CR2032, with the positive wire between the magnet and the battery. This will turn on the LED.

Now hold the larger magnet inside your shirt, and put the heart, with the small magnet attached to it, on the outside. Now it should stay put. To turn it off, just pull the broach off the small magnet.

Congratulations! You now have your own Wearable Illuminated Heart with which to impress yourself, your sweetheart, or some other worthy party. Thanks for reading!