This link came in the mailbag from one Junior Veloso, of Singapore, who has produced this very impressive homemade photopolymer-based 3D printer. Traditional stereolithography uses a scanning UV laser to cure the liquid resin, one layer at a time. A DLP printer is similar, but uses a micromirror-based video projector to expose each layer, as shown in the diagram. Junior’s version exposes each layer for four to eight seconds, resulting in print times on the order of several hours. The resin has to be opaque to prevent “shadowing” from light transmitted through the printing layer. [Thanks, Junior!]