Like it says on the tin - a device for picking up playballs after they've been scattered all over the garden.
Having a bad back, being 6 feet tall and having, most importantly, an exceptionally short attention span for mundane tasks, this is an especially loathsome job.
I thought about a large,
petrol powered, sit on thing, but that seemed out of keeping with the home and garden usage.
What about a push-around ball collector, in the style of an old fashioned cylinder lawnmower, with soft paddles instead of blades, which puts all the balls in a hopper for you. You then empty the hopper back into the ball pool.
What about a little version for the kids? (A bit like the link)