This is a Toggle Clamp for holding down a work piece on some aluminum T-slot extrusion.

I made it for working with a small drill press.  It opens and closes easily.  The screw section allows you to clamp down parts of different thickness.  The action is quite strong and repeatable.  

The OpenSCAD source files are included but the design is not quite parametric.  So if you want to make a different size it will require some serious messing around.

Print the Base, Link, and Handle with 0.3 mm layers, 3 perimeters, 20% triangular infill.

The Arm and Post should use 0.15 mm layers so the threads are clean.  Use 5 perimeters and 20% triangular infill to lower the amount of flex in the Arm.

Be careful orienting the Base on the build plate.  The text should be going vertically.  Other parts are pretty obvious. 

You will need two M3x20, two M3x40, and one M4x12 cap nut screws and associated bolts.

You could fasten this toggle onto something other than the T-slot that I used.  Just need an M4 bolt long enough for your application.