Primary Colors Old Wooden Stacking Rings Toy

I believe this old wooden stacking toy is very early Playskool--1940s or so I think, and a pretty rare one with this square base. I like its simplicity, the flat sides of the rings, and its Mondrian-esque primary color scheme, which makes it feel all the more like a small modernist sculpture. 

Plenty of wear and some paint loss around the edges especially, all to the good in my opinion, and super sturdy. 5 1/2" t x 3 5/8" w. Rings are 3" in diameter.