This loom is made from plywood and small nails or brads. My grandfather filed the heads off each nail to make them smooth and round. I know this dates to before the second world war and I suspect is was made in the depression when money was tight.
I have used this 4 inch loom but retired it years ago due to the years of wear. Look closely (especially in the lower left corner) and you can see grooves worn into the surface of the wood.