Vintage Boxwood Triangle Ruler-Engine Divided-West Germany w/ Case #241 Alvin?

Description

A very nice triangle wooden ruler for drafting, engineering, etc. It is marked:  Boxwood Engine Divided US ST’D West Germany 241. The actual ruler in the case measures 13” long. I cannot find any marks as to the company of origin, possibly Alvin. The ruler itself appears to be in excellent condition, very clean with no numbers or printing missing. I suspect that the clear plastic case is not original as it does not completely close around the ruler-the case appears to be 3/4” too short, however it is also stamped West Germany. Case slightly discolored from age. Please view all pictures as they are considered part of the description.
I recently purchased a nice assortment of unique collectibles of which I will be posting in the near future.
Thank you.