I assume you are talking about the fancy brackets. I sawed then from brass stock. This picture is from the original cart. I use what ever material works best for me. The brackets are from brass. The caps on the shafts as well as the caps on the rear of the frame are from tin. I tried to use .010 steel but didn't like the way it sawed and it was too brittle for sharp bends. The bows on top are laminated up from three layers of 1/64" model plywood. I made a form to clamp them in while the glue dried.