Pretty soon he was using silicone rubber to make two-piece, high-quality molds of lenses, good enough to try a few casting shots with epoxy resin. [Zach] ran into a few problems along the way ...

The epoxy resin is clear, but he was hopeful that some ... to wait as long as these two knobs took to make. Of course, a casting guerrilla doesn’t have to make just knobs. You can even add ...