They were presumably made in West Germany, most likely some time in the 70s. The material is solid wood. The brand is NOT "Pöhler und Schilling" or "P+S" despite looking very similar. There are no other logos, text or stickers on these things.
Any help is greatly appreciated!
I've seen those too, they are the closest thing I could find so far. The most obvious differences are that the ones from Pöhler don't have the rounded edges and are 3-way while these are only 2-way. Maybe it's a weird off-brand thing but the quality seems too nice for that.