Rainbow makers are crystals that refract light, scattering normal sunlight into its constituent wavelengths. In the same way that light is split into its component wavelengths when it passes through water molecules in the atmosphere, creating a rainbow, each wavelength of light passing through a prism is refracted by a different amount.
Different materials refract different wavelengths at different rates, so light passing through a crystal made of plastic will create a different shape of rainbow than the same light passing through a diamond. Similarly, some materials absorb certain wavelengths, so it is possible to make a rainbow lacking a particular color.
Drill a hole through one end of each prism; make it perpendicular to the length, as if you wanted the crystal to hang on a necklace. Use as small a drill bit as possible so the integrity of the crystal is not compromised, but make sure the metal wire can pass through the hole. For best results, use prop crystals made from plastic rather than real crystals, as these will be easier to drill without breaking.
Thread one 2-inch wire through each crystal and twist to form a hook. Cut the fishing wire into three unequal lengths and tie one end of each length to each hook. This will allow the crystals to hang at different lengths, like a wind chime, and to spread more rainbows at different angles.
Drill three holes in the 3-inch rod; one at each end and one in the center. Thread the 4-inch long wire through the central hole and twist to form a large hook on the top and a smaller hook on the bottom. Tie one of the fishing wires to the bottom hook. The larger hook can be used to hang the rainbow maker up.
Thread one of the fishing wires through each of the two remaining holes and tie them off so the crystals are securely fastened. For best results, hang the rainbow maker in a window where it will receive direct sunlight.
The width of the rainbow spread will depend on the shape the material used to make the prism. This is because the shape determines both the angle at which the light refracts and direction it takes through the crystal. The more spread-out the rainbow, the less bright it will be. This is because the overall strength of the light is being averaged out over a wider area.
When drilling the crystals, be sure to secure them tightly in a vice, to avoid the crystal being thrown when it comes into contact with the drill. Also, be sure to hold the drill securely and go slowly, to avoid the drill slipping. If possible, use a pedestal drill.