I would suspect they were spun from aluminum and then mounts and supporting structure added. Much the same way they are still made. Here's a modern spinner being made.
https://www.youtube.com/watch?v=yrTDBW6q7Xg
I've been sneaking in here and enjoying the beautiful projects and great information for some time now. Thought it was about time to join in and introduce myself.
I've been interested in all things mechanical since I was very young. Love steam and vintage gas engines. This a great hobby to...