This is a parametric 'T' clamp hold down for use securing work on a CNC mill table or similar.
My assumption is that you will use M5 screws to hold down the clamps. If you want a different size screw, it should be easy to change the slot width.
It has a nose cutout so that it can be used to secure thin sheet work. If you want to remove the cutout, you can modify the openscad script and change the "nose" variable to false.
You might want to print these at 60% fill or more for strength.