Petrus paper punching machine guide

I have an old paper punching machine that used to have a plastic piece to position the paper in order to ensure the holes are where they are supposed to be.
Well, that plastic thing has been missing for years, so I decided to make one.
It is such a simple and geometric thing that I figured the easiest would be to make it with Openscad, using cubes, cylinders and spheres.
I leave the openscad code, I did not even bother to define variables.