I work in a vibration testing facility and there are so many machines that I could very easily make into a sex machine, although the safety aspect of using such a thing would worry me way too much.
I am surrounding by things like this on a daily basis. http://www.mts.com/en/products/producttype/test-systems/load-frames-uniaxial/servohydraulic/standard/index.htm
Realisticly anything with a reciprocating action can be used as a thrusting machine, and a lot of people have made toys from cordless drills.
https://www.youtube.com/watch?v=vj17JK1lsNs This is what people have done before.