[MrForbes]

It will be interesting to see how changing the height of the roller and ingress of the ball affects it. I can see how it could be a problem if we have the ball not in so far, so we'll work on prototyping a more legal version real soon.

Thanks for the input Sam.

btw the roller in ours is ABS pipe covered with spray rubber, which is a product designed for coating tool handles and such.