Not exactly sure. It is a hard almost brittle plastic. There is a painted barney next to the set that is obviously from the same mold as the clear but of a less brittle feeling plastic
Those were produced by Empire Plastics in the late 60s/ early 70s. Dime store and vending machines mostly.Hard extruded plastic injected into molds. If you look at them close up you can see all kinds of imperfections in the finish. They did a lot of different figures. Snoopy comes to mind, but not the rest of the peanuts.