Radius measuring templates

This is not particularly innovative but I made a quick set of radius templates out of plywood, marked with their respective radii in mm. I’m milling an adapter plate that connects an EMPI Weber air cleaner to a Datsun carburetor, and this was an enormous help in determining the curvature of the air cleaner inner and outer radii for modeling preparatory to milling. I drew them in freecad, using its constraint manager to produce the precise radii I wanted, and imported that into inkscape to add the text as a second layer.