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 ...

These went into a clever 3D printed mold box, which was small enough to put into a food vacuum container for degassing purposes. The shape of the buttons necessitated a two-piece mold, into which ...