Laser-cut fixture for milling polycarbonate by MarkU - Thingiverse

Instructions

You will need 10 M6 x 20 mm bolts, an M6 hand tap, and some T-nuts to hold it onto the mill bed. This design is sized for A2Z Tuff Nuts and a Taig DSLS3000 CNC mill.

Laser cut. The perimeter hex bolts (M6) will go through all the layers except the one with no center cutout, that is the bottom layer. Use an M6 hand tap to thread those holes. Use T-nuts and appropriate bolts through the end holes (not sure of the exact length, I used some shorter #10-32 ones I got with the mill) to fix this plate onto the mill bed. Stack two of the plates with center cutouts, then the spacers (long thin bits), then two more plates. Then add the M6 bolts, slide your polycarbonate strip in the end, and tighten to clamp.

NB the fixture shown in the picture is version 1 which does not have access to the T-nut bolts through all 4 plates, version 2 is modified to include that to allow mounting & dismounting without having to completely disassemble the fixture.