Just a quick one this time. Here’s a simple lasercut design for a ‘contact goniometer‘ which is used for measuring the angles between two faces of a crystal.

It’s lasercut from 3mm acrylic, and to make the engraved text stand out, I rubbed green acrylic paint on the surface, then wiped it off before it dried. The paint stays in the engraved sections and highlights them nicely.

By holding the edges against the crystal face, both the direct and internal angle can be read out. I was originally only going to include one scale, then I realised various people use different conventions.

The object I’m measuring in the photos is the excellent 3d printed quartz crystal by Pmoews here.

Files up on thingiverse for anyone that wants to make their own.