From the Loftsmith community

R45 radius gauge

Checks a rounded corner or edge against a known curve, so you can see at a glance if it's too tight or too loose. The curve is cut into one edge, with R45 marked on the face and a small hole to hang it up. Change the radius to match the curve you need.

1 part · 6 g · 70 × 57 × 3 mm