Those are AC Gilbert molds, Gilbert of Erector Set fame. I can't remember right now the name under which they sold their casting set, but I can check my copy of O'Brien's "Collecting Toy Soldiers" when I get home later this afternoon. It might have been "Kast-A-Toy".
There were other molds in the set, including a mounted figure, a ship, and I think, an airplane. The molds are all the same size, square, and they fit into the rig that came in the kit.
Hope that helps, prosit!
Brad