This equipment was previously owned by a now-retired coworker. Whoever enlarged the window did an impeccable job. We're mostly engineers, scientists, physicists, and machinists here, so there's a good chance it might have found its way into a water jet, wire EDM or laser cutter. Then again, in with the pile of darkroom equipment I got is also a homemade 6x6 negative carrier made out of matte board, and it looks like it was made by someone with a butter knife and a cast on one arm.