Simple yet very useful tool for getting your strings and pick ups where you want them.
If slightly rough edge, some ultra fine sandpaper is in order to smooth the surface just a tiny little bit.
My suggestion is to do the measurements in a well light area and working on an adequate height to avoid angles of sight messing with actual measures.
Maybe for next model, it would be a substantial improvement to make it in some lively color with same black stripes measure lines as it has now.
A great little tool that you can always take with you due to its credit card size.