T slot clamps?

Mostly Printed CNC - MPCNC Hardware Development
1

Has anyone tried/seen these?

http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=391418396743&category=41945&pm=1&ds=0&t=1459398986357

I’ve been trying to figuar out what I’m gonna do for clamping stuff down and thought these might do the job. Or print something like them