When I build automata I always try to have the handle relate somehow to the subject of the piece. This is not always simple because I usually try to find something with a slender aspect ratio, that is, long and skinny. I have used odd shapes but they seem a little awkward for people to turn. The other constraint is I try to have handles smooth on one side since I use a motorized push pin to spin the handle around when displaying as shows, so I can relax and chat to visitors.
Anyway I was struggling a bit to come up with something that either related to sheep or jail for my current project. I settled on a skeleton key as might be used to lock a cell door. The shaft had to be a little fatter than normal for strength, but I managed to fashion one that I originally thought reasonable. I glued it on with temporary latex adhesive to try it out and take a look at it in place. It didn't take long to realize that I was not happy with it and I set out to think of another design.
After drawing a blank for a while I settled on a "machinery type" crank, themed it toward sheep. So below is a picture of a "cast iron" handle made by the Ovine Manufacturing Company. I am happier now.
Automata is a creative blend of my life interests , engineering, art and woodworking.