Bed Level Clamps Rough

OK.. too busy to do that automatic version, so here is a clamp design to do the same thing manually I hope.
set you Z just above the bed (say 1mm), loosen all four clamps (stl's coming soon, 2 as the one shown, two mirrored)
Move to first corner, lower it 3 mm or so and tighten the clamp for that corner, repeat for all four corners, set extruder z height at that height for your zero...

This is specific for the Makerfront prusa i3 steel.

You should need one M3 screw and two M3 nuts for ea