There are some types of projects that we see quite often here on Hackaday; 3D Printers, Development Boards and Video Game Hardware to name a few. Once in a while we see an optics-based project but those use pre-made lenses. [Peter] felt it was time to give home lens manufacturing a shot and sent in a tip about his experience.
The typical lens manufacturing process starts off by taking a piece of glass and manipulating it into a rough lens shape, either by removing material or heating the glass and forming it in a mold. These lens blanks are then lapped using progressively finer grits of abrasives until the final lens shape and surface finish are achieved. The tool used to lap the lens is very specialized and specific to one lens contour shape. This lapping process can be very time consuming (and therefore expensive) depending on the quality and size of the lens being made.