Cosmic Light With LEDs Embedded in Resin

Step 7 Build Up the Sides of the Box

Cut 2 strips of cardboard that are about 6.5 to 7 inches long and 1.5 inches wide. Tape them together with masking tape. Then wrap the whole thing in waxed paper and tape it, making sure one side is just smooth waxed paper with no tape or other texture.

Using the small clips, attach this strip of cardboard to one of the long sides of the mold, as shown. Three clips along the bottom, one on each side. Use the lip of the mold to make a seal between the cardboard and mold. Trust me, resin is very viscous and it'll hold. You'll set the mold on this edge (on top of something so that the side of the mold is parallel to the ground). I set mine on the box of waxed paper. I also ran a strip of masking tape from the now top of the mold to the table to prevent it from accidentally falling over.

Be sure you do this over some scrap/newspaper because it is possible to drip a bit. Mix up 1/2 an ounce of dyed black resin (add glitter if you'd like, it'll fall to the bottom and show in front of the black). You'll pour this over the cardboard to fill in the side of the mold. It'll be about 1/4 of an inch of thickness for this wall. Leave the whole thing set up this way until the resin hardens up. Then unclip it, carefully peel back the cardboard strip and repeat. I used 1/2 ounce for each of the long sides and 1/4 ounce for the short sides.

Again, leave it overnight to get solid because you'll abuse it tomorrow.