It may not be sensible to do some of the suggtested things but its great fun to think of and sometimes that helps engage the sense of humour to help get through the situation.

If you have access to the permanent art of a class of six year olds you could use them as garden sculptures. That way the kids get the thrill of seeing their stuff on public display and your neighbour can only look like a complete grump if she complains. My mom got upset once and wondered what the neighbours would say when I let my kids play with sidewalk chalk all over the driveway. I couldn't understand her concern; across the road is a marvelous gardener who is allowed to let her artistic and creative abilities run rampant in public view, why shouldn't my kids be allowed to do the same? The rain washed the problem away.