Customizable Center Finder

I remade the whole thing in OpenSCAD inspired by the source. I still consider it a remix as I did not come up with the idea myself.

My improvements:

* Fudging factor to avoid rounding errors (creating infinitely thin top/bottom layers in cutouts)
* Cross-"beam" supports
* Customizer compability

Open it in the customizer interface to create an STL (all measurements are in millimeters).

Default values creates a center finder for up to 70mm wide surfaces and an example STL is included in the files.