I'm using these to clamp workpieces to a captive nut table made from a 10mm thick PVC scrapyard plate. The table was made by the CNC itself by milling a matrix of pockets for M5 hex nuts and the holes (or round pockets) in the center. A DXF drawing of an M5 hex nut can be found in the thing files section. You can multiply the toolpaths in Estlcam (or whatever CAM prog you are using) to get the right matrix for your needs.
A threaded rod of about 70-100mm and a winged nut together with aluminum bars is what I'm using as a clamping system.
The wooden bars provide some offset to the clamping table and make the Z axis shorter during milling jobs which should make the machine more rigid, assuming the clamping is perfect.
Printed from ABS with a low infill.