The Wright-Regan Instrument Company (Wrico) was one of the leading manufacturers of lettering templates for many years. Aside from their own line of products, they also did custom manufacturing.
A series of lettering guides called “Mimeostyle” for the A. B. Dick Company of Chicago (produced for use in making mimeograph machine printing stencils) featured an art Deco squared letter design with rounded corners.
This is now available digitally as Template Sans JNL, in both regular and oblique versions.