I designed a toe clamp for my CNC. My CNC spoilboard has 1/4-20 threaded inserts spaced 50mm apart. The downward angle of pressure is 4° providing a solid clamping force. I can't believe the amount of clamping force these things have even with hand tightening. The parts used were:

2 - 1/4" 4" rods threaded at ends (I used brass) 1 - 1/4-20 threaded insert 1/2" in diameter inserted in front end of body 1 - 1/4-20 threaded socket screw 4" 2 - 1/4-20 square nuts 1 - 1/4-20 lock nut

and the printed files.

I used PLA printed with 50% density and no supports with a raft.