This project was my daughter's idea: a cast wax dragon with LEDs inside. You can, of course, use a different mold, but we had some really nice silicone Chinese dragon molds that we got on ebay a long time ago (from a seller that alas seems no longer to be in business) that have held up to many plaster and wax casts. If you can't find a good mold, you can always 3D print something out of wax.
- Chinese dragon mold
- candle wax (we melted down some old tea lights)
- piece of red crayon
- microwave safe cup
- microwave oven
- medium box
- stirrer (e.g., plastic knife)
- box cutters
- 2xAA box
- drill with some drill bits (or just the drill bits--you can drill wax by hand)
- two bright red LEDs
- electrical tape
- solder and soldering iron (or heat shrink tubing and source of heat).
The method we used here was to drill holes in the dragon for the lights. As we were getting close to done, my daughter noted that we could also have inserted the LEDs in the molten wax instead of drilling. If you go for that, you'll need some toothpicks to suspend LEDs in the correct positions without them touching the outside.
I wouldn't leave this on all night, its being made of wax.
Step 1: Wax Dragon: Preparations
Before you start melting the wax, cut a hole in the top side of a cardboard box for the mold to sit upside down in. Put in the mold, making sure the bottom is level.
We used wax from four tea lights that had melted together in the cupboard (we had enough left over to make a slightly shorter red tea light).
Pull out wicks, put in microwave safe dish, and microwave until it's mostly melted.
Then add a bit of red crayon. I used basically all of the sharpened tip cone of the crayon.
Continue microwaving until all is melted.
Step 2: Wax Dragon: Casting
Container will be hot. I wore safety glasses and used oven mitts when I had to pick up the container.
Carefully pour into mold, level with the top. Stir to fill all the details in the mold. The wax will shrink making a convenient hollow, which will help fit the wiring.
Leave to cool. Once it cooled somewhat, I transferred to the fridge.
Step 3: Wax Dragon: Demolding
I had put it in the fridge for the final cooling. But I couldn't peel the mold off while the wax was refrigerated, so I took the mold out of the fridge to return to room temperature. I guess it wasn't necessary to use the fridge at all, but it may have sped things up.
Carefully peel the mold, watching out for details that can break off.
In our molds, there is no avoiding breaking the top half of the snout of the dragon. Any broken pieces can be welded back on by melting the wax on both pieces with a hot knife. (I just used a butter knife that I heated over a hand sanitizer flame on a piece of aluminum foil.)
Step 4: Wax Dragon: LED Holes
Now it's time to drill a hole for one LED in the neck/head area, and to scrape out a depression for an LED near the tail.
After choosing the drilling direction carefully to ensure that the tunnel would not break surface, I drilled on a lower speed with successively larger bits. For the largest bit, I just spun it by hand.
Then my daughter scraped out a depression for the LED near the tail using the drill bit. I ended up carving out more room for wiring on the bottom later with a screwdriver.
Step 5: Wiring: Prototype
I had a Radio Shack switchable 2xAA box and some super bright red LEDs. The specifications on the seller's website gave the current and voltage drop (I also measured the latter) which I put into an LED calculator app to find the resistor values corresponding to the 3V box. Since my voltage drop was more than half of the supply voltage, the LEDs had to go parallel, and the calculator called for a single 25 ohm resistor connected to the two parallel LEDs. I didn't have a 25 ohm resistor, so I just put two 47 ohm ones in parallel for an effective 23.5 ohm resistance.
I laid out the simple circuit on a breadboard and made sure that the LEDs were sufficient to light up the wax dragon.
Step 6: Wiring: Final Version
I soldered the two LEDs in parallel, long lead to long lead (positive) and shorter lead to shorter lead (negative, also marked by flat on LED edge). I soldered them at right angles to each other, as one would be going into the dragon and the other along the bottom.
You should now make sure the wires from the battery box are just the right length for the box to sit under the dragon comfortably. I initially had wires that were too long and there was too much wire under the dragon for it to sit on the box. (The pictures here show the longer wires.) I ended up having to cut the wires in half.
I soldered the minus wire from the battery box to the long leads, my 23.5 ohm resistor (made of the two 47 ohm ones twisted together) to the shorter leads, and the positive wire from the battery box to the other end of the resistor.
I put on some electrical tape to prevent shorts.
Step 7: Final Assembly
I stuffed the LED into its hole, pushing with a screwdriver as needed. I laid the other LED in its depression on the bottom. I enlarged the depression on the bottom of the dragon to fit all the wiring, and laid the dragon on top of the battery box.
The switch ended up under the dragon, which is fine as the dragon simply sits on the box with the wires tucked in and can be lifted to turn the switch on and off. The alternative would have been to put the switch on the bottom and to make four legs for the battery box to stand on.
The photos don't quite give justice to the richness of detail on the wax (no thanks to me--the molds I bought had amazing detail).