E “Zelluglas”

Data:
It could be a “one of a kind” but a lot of work and attention has been put into it both in construction and composition. Some details:

• Length 264 mm, thickness 9 mm
• Material construction : Aluminum, wood and paper (plasticized) held together by rivets. The runner is Bakelite and glass.
• Front panel features scales K, A, B, C, D and L.
• Reverse side an outline of various constants.

There is no name or manufacturer affixed but on the reverse is the marking “Zelluglas.” Further, the D.R.P. marking is present.

Questions:

1. Has anyone ever seen this slide rule? It makes me suspect that it comes from German-speaking country because of the descriptions on the back
2. Who made it? “Zelluglas” is not found as information in relation to slide rules.
   In 1955, a German Gebrauchsmuster DE1712702 for a cardboard folder with Zelluglas-cover was issued to “Zelluglas-Plakatfabrik Druckerei Walter Hülter, Wuppertal.” Walter Hülter was issued a lot of patents and Gebrauchsmuster for “lacquered/varnished/coated posters” and other advertising items. Andries de Man
   The “1” scale annotations at either end of all but the L scale + the style of the tick marks is reminiscent of a Rietz slide rule made by a little known German maker W. Ball & Co. from Aachen (Herman’s Archive & Hopp). David Rance
   Is there anything useful in Karl Kleine’s DRP file? David Rance