My guess is Steyr got the idea from the Walther. The Steyr grip material was actually from repurposed cheese crate slats. This was shared with me back in the latter 1970s when I visited Al Hoffmeyer, whom was a Radom collector. He removed a grooved wooden grip from one his Steyr T3 pistols. On the back side was most of a triangular paper label (auf Deutsch) stuck to the wood depicting a Rhine maiden and advertising "Velveeta" cheese!
