I am currently trying to attach a small flat piece of plastic (no bigger than 2", could be smaller) to a 1.9" hollow aluminum tube bent into a 2 foot radius torus, spinning at 2Hz. My first and normal approach would be to drill a tapped hole in the hollow tube; however this is not an option in this situation, as the inside of the cylindrical tube is kept in a vacuum, and has to be in order for the project we are working on to work. My second approach would be to mill the plastic to match the diameter of the tube, but the problem remains; how would I attach the resulting plastic to the tube?
I have access to a machine shop, so I can do some basic mill and lathe stuff in order to accomplish this. How should I do this?