I have a rubber wheel that has a 1/2" plastic bore with a key slot in it (see attachment). I want to spin that wheel with a motor that has an 8mm straight shaft. I need some ideas on how to fasten the motor shaft to the wheel. I want to have a bearing opposite of the motor to keep the shaft from wiggling. My idea was to get a custom hollow shaft made with a key slot in it. That way the hollow part will slip over the motor shaft and the key slot will will utilize the slot in the wheel. Is that a good idea? Is so, where are some good places to get custom shafts made? If not, what are some better ideas.