My wife did the glass for these doors. The consignor told her what all he wanted on them. It is all glass. Powdered glass on sheet glass and fuzzed at 1440 degrees.
This piece was done in sections and leaded together like any stained glass window. She has a 6 x 3 foot kiln. Glass has to be heated and cooled slowly to keep from shocking it. Too much shock and it shatters. The bigger or thicker it is the slower you have to go.