This glowing crystal Kryptonite was a project for my son and nephew's high school Robotics team, CRyptonite Team 624 from Cinco Ranch High. (Team CRyptonite was originally named to combat a rival who uses the Superman logo).
Robotics tournaments tend to have some excellent swag for the teams, and I wanted to do something that catches the eye, intimidates the opposition, and represents the team. The crystals look good without light but they really pop when they are lit up. We light the crystals with a solid LED glow until it's game time and then we switch to frenetic blinking during the match. I'm pretty sure it helps the team, and at the very least we win the battle of nerd-swag every time.
Step 1: Gather your supplies
The Kryptonite crystal is made by molding a prototype with modeling clay, then creating a silicone mold, then casting it in resin. I added an LED light with a 3 speed switch and a chain to make it a necklace but it works great as a nightlight too.
1. Oven hardening modeling clay - Hobby Lobby, $8.
2. Easy Cast clear casting epoxy resin - Hobby Lobby, $24 for the jumbo pack will make 4 clumps of Kryptonite
3. Castin' Craft color pigment OR food coloring - Hobby Lobby, $5. I colored some batches with the resin coloring, some with food coloring, and some with both to give differentiation between the necklaces.
4. Easy Mold liquid silicone - Hobby Lobby, $19
5. LED lights with switch - I priced out LEDs and micro pcbs but it was more economical to buy ready made backpack lights at 3 for a $1.00 at the dollar store. I trimmed the plastic case and removed the strap, voila - cheap and easy multi-speed lights.
6. Chain (for necklace) OR optional base (for night light) - I used light fixture chain from Home Depot at .90 cents/ft.
7. Scrap wood or cheap plastic bowls, masking tape, and plastic cards to make the mold case.
Step 2: Form a crystal prototype from Clay
Spread out a piece of freezer paper and tape it to your counter or tabletop. Unwrap your modeling clay. You'll need to knead the clay to make it soft enough to form your crystals. I used a spare piece of PVC as a rolling pin to soften up the clay. To form my crystals I rolled thick lengths and cut it with a sharp knife to create faceted lengths. I cut the crystals into assorted lengths and squished the ends together to create a crystal cluster. I finished it off by using toothpicks to smooth and shape the intersections of the crystals. I made 4 different clusters so that my Kryptonite Nerd Swag necklaces would have some differentiations.
After my crystal clusters were formed I baked them in my oven at 300 degrees for 20 minutes and then let them cool overnight. I used tin foil to ensure that they would not stick to the cookie sheet. The clusters were cool, hard, and ready to go the next morning.
Step 3: Build a mold box to create a silicone mold.
Use a piece of basswood or scrap wood to create a mold box, or just use a cheap piece of plastic ware slightly larger than your Kryptonite. Creating a box will let you use the least amount of silicone necessary for your mold because you can create a custom sized box that will fit your crystal closely. You only need a 1/2" of silicon at most around your crystal to create a mold.
I had an extra piece of basswood so I just cut it to form a simple box. I cut the four sides and used masking tape to hold them together. I then taped a basswood bottom to the box and sealed it with masking tape. It is important to not have any gaps because the liquid silicone will ooze out of the box. Using masking tape makes it easy to de-mold the silicone without damaging the silicon, you just untape the sides and peel them away from the silicone once the silicone has set up.
Step 4: Pour the silicone mold
Take your Kryptonite crystal and use a hot glue gun to seal it to the bottom of the wooden mold box. Be sure there is at least 1/4" of space around the crystal to create a thick enough mold. Mix the silicone with the catalyst from the box and stir thoroughly. My first attempt did not set up correctly because I didn't mix the silicone thoroughly, so trust me you need to scrape the sides and mix for 2 solid minutes. Once you've mixed the silicone, pour it slowly over the crystal. This will help the air escape which will prevent bubbles in your mold.
You'll see in the picture that I had some extra space in my mold box. I taped two plastic cards into the open corners to avoid wasting silicone and having an overly thick/less flexible mold. I also ran short on silicone by the time I poured the last mold, so I had to displace some silicone by pushing little pieces of PVC (taped shut on bottom) which raised the level of silicone just enough to cover the last crystal. In retrospect, I should have done this on all 4 molds because the thinner mold was much more flexible and easier to work with than the full-box molds. Live and learn.
The mold needs to set for about 4 hours before you can remove the sides. I actually waited overnight because I wanted to be double-extra sure. I removed the taped sides and pulled the silicone off of the bottom of the box. You'll need to tug the sides over the crystal to pull it away completely. The silicone creates a vacuum seal onto the wood and clay so peel the mold from the clay crystal to break the suction before you tug the mold away.
I taped the box back together after removing it because I wanted to keep the box for future pours. The box also makes a good place to store the silicone mold.
Step 5: Pour the resin in the silicone mold
Mix the epoxy resin in a throwaway cup. Add pigment and food coloring to get the color you want. I used different shades, light and dark, to make my crystals all slightly different. Mix the resin and color thoroughly. Pour the resin into your silicone mold slowly and carefully. Once the mold is full, set it aside for 24 to 72 hours to cure. The resin really smells while it sets so you may want to leave it outside if the weather cooperates, otherwise be sure to open a window nearby.
When the resin has hardened, peel the mold gently away from the crystal to break the vacuum seal. Tug the silicone over the crystal shards one side at a time to work the crystal out of the mold. Set the silicone mold aside or store it in the mold box.
Step 6: Add the light and the chain
Next, I took the backpack keychain light and stripped it down. I trimmed away the strap, loop, and extra plastic from the case to make it as small as possible before I added it to the Kryptonite.
I used a Dremel to carve a flat depression in the flat back of the crystal. The depression should be just large enough to inset the backpack light. Next, use the Dremel to carve a groove to inset a chain link. Use your chain to trace a pattern onto the Kryptonite before carving.
When the carving is complete, clean the back of the crystal and superglue the chain and light into place. I topped the area with a layer of hot glue to create a level surface on the back of the crystal.
The backpack light already had a 4 way button (fast flash, slow flash, solid on, off) so I didn't need to make my own. That was vaguely disappointing but in the end it made the project faster and cheaper to buy a ready made LED light and strip it down to fit my project.
If you want a nightlight or mood light instead of a Nerd Swag necklace just mount the crystal on a simple block base. It also looks neat just sitting on a shelf without a base. Another variation is to leave the resin clear (don't add the green coloring) and use a RGB light to make the crystal change colors. I've told myself that as soon as I finish the last of these 100 necklaces, I'm going to reward myself by casting some clear crystals and building my own light show PCB version. That might be a different Instructable. For now, enjoy your glowing shards of Kryptonite. If you've enjoyed this Instructable please vote for it in the Make it Glow contest. I could seriously use a 3D printer for these little projects. Until my next post, Go Team 624 and Death to Superman!