Not exactly 'test benches', but in the same vein. These were built back in 2010 or so. One of these is built into a cheap Ikea basket, some plexiglass and scrap metal - plus some old case parts. Also used as both a NAS and media center PC.
The other was built to attach to a 200x200mm VESA mount, again using plexiglass and scrap metal. I believe it was a Hackintosh running Snow Leopard.
Both of these collected dust like you wouldn't believe.