This is basically a remake of phineasjw's Replicator Bed Level Jig in OpenSCAD. It's not as fancy, because my patience with OpenSCAD ran out, but it does work.
My dial gauge was too short for the original. With this one you can make a custom jig that suits your dial gauge diameter and length. You can also customise holes for the magnets.
dial_gauge_jig.scad | 3.8KB | |
dial_gauge_jig.stl | 255.1KB |