I started this off with a little contraption to throw the balls around.
When I got tired of resetting them manually, I used the transportation mod to recycle the ones that fell into the little box.
When I started throwing them around the whole map, I setup a river dredging system to scoop them out of the water and bring them back to the box.
The save can be found here if anyone wants to try it out: http://www.garrysmod.org/downloads/?a=view&id=109497
*Warning: need a decent computer or it will lag bad.