Tech Ether Guild
A few examples of belt buckles by the Tech Ether Guild. Rare designs include Saguaro, Earth, Crystal, Fleur De Lis, and many more.
Trinity Buckle Co.
The early Trinity belt buckles were only marked solid brass. Some of them are very hard to find and I've kept a few of the coolest ones for myself.
STAR BUCKLE BRASS & PEWTER Co.
BTS (Basic Tool Supply)
BTS manufactured belt buckle blanks and marketed them to artists and craftsmen so they could be completed by engraving, adding stamped leather inserts, or by filling them with stone inlays and epoxies. Some of their standard retail designs were also finished and resold with stone inlays. I don't believe these are factory/stock, but the inlay is high quality and I've kept several like-new condition examples for myself.