On my test chassis I wanted a way to couple my enclosed rotary shaft encoders to the shaft on the AndyMark gear boxes. So we tie wrapped a piece of automotive hose around the shafts on either end making a 1 foot long flexible shaft coupler that goes back to a brace in the middle of the robot.
I was concerned it might slip but it does not.
I was concerned the misalignment from end to end might cause it to lash, but it does not.
It is janky (jenky sp?) and I like it.
That's not quite as bad as the day a friend and I put a model airplane prop on a weed-whacker small engine clamped to my deck to test something. What could ->possibly<- go wrong there? (Leave that dumb trick to the professionals okay kids!)