Last year at a garage sale I scored an inflatable ball pit complete with a couple trash bags full of balls. The ball pit has several holes that we patched. All was well for a few weeks, but then the pit started deflating again. Despite our best efforts, it just had too many holes to be salvaged. So we stored the balls in a laundry basket. This meant they spent more time dumped on the floor than actually in the basket - not so fun to play with :p We looked ALL over last summer for one of those hard plastic swimming pools, but were unable to find one. Finally my husband said "you know, I could just make a pit..." My response was "this weekend?" So he did. I assisted. Sort of :)
This is the finished ball pit - cool huh?
My incredible husband built a wooden box with wood we had on hand. Then we got 1" foam from Joann fabrics and stapled it around the top. We covered the entire structure with vinyl (easy to clean!) stapled nicely.
Then he inserted the pvc/net from the inflatable pit and we filled it with balls. We were going to put a rug in the bottom of the pit, but we forgot so it's open to the floor. My boys LOVE it and I love that the balls are contained where they can enjoy them :)