You may have seen a pulsable spin button toy [link] I think the same thing with a two finger loop as well as a pawl (or other simple gearing) would vibrate. Make it out of silicone to be soft and vibrator like and it becomes a finger powered pulsing vibrator. Just made of plastic it could be about 4 cents per sexual pleasure vibrator.

wet glide strips, made from polyurethane oxide and polyvinyl pyrrolidine could be used as a wet slippery glide surface coating on the two finger all polymer buzz vibrator.
-- beanangel, Dec 15 2016

spinning button toy http://www.instruct...d/Spinning-Button-T
[beanangel, Dec 15 2016]

It takes a certain imagination to see a spinning button toy and think of marketing it as a cheap way to rub one out.
-- tatterdemalion, Dec 15 2016


imaginative [+]
-- Voice, Dec 15 2016


Even with mechanical advantage, your going to have two fit,oversized muscly fingers. It won't do the other sets of nerve groupings.
-- wjt, Dec 16 2016



random, halfbakery