The escutcheon and the outer/bottom body of the MK3 are also Al, but obviously thinner.
The ultimate would be to remove the motor from the escutcheon/body and mount naked, which a couple different aftermarket plinth manufacturers have done, as that would illuminate all the distortions that they pick-up and add.
This can be done easily with the MK3 as the electronics are all in the isolated controller and the speed and start/stop buttons on the escutcheon can be eliminated.
@rich121 Yes, if you moved the motor and electronics into a plinth which includes the base of the arm, and the whole thing was both rigid and acoustically dead, it would be fabulous.