I have an 8" CBN (Carbon Boron Nitride) wheel on my bench grinder, and I needed an accurate angle guide for my woodworking chisels.

This guide has 4 different angles: 17º, 20º, 25º, 30º

The ends of the guide are purposefully arc'ed to rest against, fit, and conform to the 8" diameter of the wheel. Normal grinding wheels wear with use, reducing their diameter, but CBN wheels don't (well, practically speaking), so the end of the guide should always conform to the wheel.

I printed mine in PETG-CF, and the included print profile is for that filament, but just about any filament will work. Tweak the setting to match your filament.