Corner clamp MkI remix

Remix of Corner Clamp MkI . I've changed two things on the screw. 1: I've added 4mm hex hole on the knob side so it can be screwed in with a drill or driver with 4mm hex bit.2: re-tabbed the other side so M5 screws can be used without being way too tight. I've used M5 x 20 for the adapter to screw, and M5 x 8 for the other one.