Drilling jig to drill a hole in the middle of a hole of another jig.  (The other jig is here https://forum.copaindescopeaux.fr/viewtopic.php?t=14008 sorry in French.)

The openscad source files are attached, if you need to change the size of the hole, change the internal_diameter (or any other variable)  in config.scad and re-export the stl file. 

I used this jig to prepare my mft workbench.