To those using rollers:

[DonRotolo]

We are not using rollers of this type this year, but in the past we have cut a plug of 1" thick wood and forced it into the end, and secured it with a small wood screw through the plastic into the wood. The center of the wood can have a hole in it, or a plate or hub mounted to it, to interface with the motor or gearbox shaft. Alternatively plastic can be used, but we found that wood was stronger/easier/tougher/lighter/cheaper.