The Traditional Fisherman's Forum

A 'bouncing betty' could help you to start with. They are used to keep in contact with spinner/plugs and prawns when salmon fishing. There are two sorts available - a round rubber ball in 0.75in - 1in - 1.5in sizes. The alternative is a like a biro tube with a swivel at the top and a weight at the base.
Both are able to move downstream over gravel/small rocks.

Having used them for the above I have tried and successfully used them for rolling meat for chub & barbel both on the Kennet and Hants Avon.