Cut apart a worn out Engine mount just to see whats inside.
On the Engine mounts I make, I take a piece of pipe and weld a washer on the end. Then I weld a few lumps on the pipe for the rubber to grab onto. Was just curious to see what Honda did. Apparently a piece of pipe with a washer.
In the pics below the white Engine mount (worn out) is the ones I make and the black one is the Honda unit.
CO

Didn't someone measure the durometer in the past?

It wouldn't be hard to make a mold for these. You could likely cnc machine a mold out of delrin.