Mantis Clamp Gridfinity Stand

Remade the mantis clamp's stand to be a proper 1x2 gridfinity module.

Also including a variant that has a hole cut into it for a rounded 14x44x14 steel weight that I happened to have on hand; good luck sourcing one tho...

OpenSCAD using BOSL2 source code for the adventurous: https://github.com/jcorbin/3dp-misc/blob/main/mantis_clamp_holder.scad