This process is fun!

You take a piece of Dalle de Verre glass (Dalle de Verre is French for slab of glass, but it sounds much better) attach it to a frame and then carve the glass with an angle grinder. Dalle de Verre glass is 12" X 8" X 1". The more you carve the glass the thinner is gets, so the lighter the color becomes. You have to be very careful not to work on a particular part for too long otherwise the glass will heat up too much and crack.

Working on glass like this is loud and messy, you have to wear earplugs and a face mask, but it is fascinating to watch it take shape.