Internet searching for centre caps, when I came across a great tool for helping to measure from the centre point of your wheel to the arch, specifically for when lowering your car on coilovers.

I found his 5 stud version over on Cults 3D, but [either I didn't see it or it wasn't uploaded at the time of searching], I thought I'd have a go at designing my own. Once I've used this set up, I don't expect to use it again. Credit for this original idea goes to YosHRDworld over on Cult3D .

My version is for a 4x100 PCD, wheel bolt hex 17mm.

Images show assembly. The 'wheel centre datum ring' will require to be glued on carefully to allow rotation of the ‘wheel centre datum’ piece.

All other pieces are a designed to fit together loosely to allow movement, the ‘wheel nut location pin rings’ are a tight fit.

There is a version for those with dual filament printers if you want colour, this is how I printed mine. But it's not essential to the operational use of the gauge.