the binder was machined into the clamp as one-piece. the extension is 1" X.120 wall, ovalized and the quill is a lathe made part. The whole thing took about 20 hours. Lots of filing.
Aluminum transfers heat very quickly. Gas welding is very effective for sheet metal work and works a lot like steel brazing with a unique flux. Typically 1100 series filler is used as are special glasses. It is very difficult to get a thicker piece hot enough to use this method.
that brass tool is neat. I don't think I have tried to gas-weld brass.