So do the kids just go and get the ball themselves? My kids wouldn't see the light of day for a week if i caught them going on to somebody's property without their permission.
Could you maybe form something using chicken wire? Wouldn't stand up to too much punishment I guess, but would maybe reduce the impact - if you added a few spikes on the top to punture the ball, mightened be a bad thing either.
I am not anti kids by the way , I have two boys aged 8 and 7 that are not averse to a bit of football, but unless the are playing with a foam ball, they need to take it to the playground or I take them to a park. It's all about consideration for others. My neighbours little boy regularly kicks a rugby ball around the street and despite me telling both him and his parents on several occaisions that it is not suitable to play with it in the middle of a housing estate, he still does. It is only a matter of time until he breaks a window or damages a car and then they will know all about it!!
What about this?:
http://the-plant-directory.co.uk/greenhouse-mi ni-4-tier-p-2401.html?zenid=f3ba4419618463a3aa a4036c58483291