Spring loaded adjustable PCB Holder

I make, test and populate a lot of PCBs. I make jigs to hold them from time to time. Here is one of them. Tried to sell it on eBay for like a dollar a piece and no buyers yet. Oh well, there loss. ;-)
So, I figured I'd make the files available to fellow tinkers.
I've tried several springs. Seems the .390in radius fits the best. In terms of force, somewhere between just holding the PCBs and breaking the fixture should due. :-)
Happy building.
Bill