Well this was our big Christmas project. I saw this here http://www.cupofautism.blogspot.com/2013/09/this-weekend-has-been-blast-we-made.html It was pretty easy to make. I sewed the cargo net (from Joann's fabric) and my husband cut the pvc and assembled it. We plan on getting slides for entrances and exits. Note that the pit is a little bigger than 4ftx4ft because of the connectors. Ours is like 53inchesx53inches and about 27 inches tall. Not sure how long the cargo net will hold but the entire family, including the dogs can fit in this thing! The girls LOVE it! It's only half full with about 2500 balls now but poor Ruby is neck deep so as of now we can't add anymore until she grows.