Ooooh..... this is awesome. I actually had my GF keep her boxes from moving recently, and I just haven't gotten around to it.... but I'm planning on making a maze possibly this weekend! Some great ideas here to keep me from making (as many) silly mistakes!
I also found out a friend of mine works in shipping and receiving at his job, he's described a large dumpster reserved just for cardboard (all undyed, matte, the good stuff!) that they have to empty at least once a week. Yay for neverending supply of cardboard! They also have 4'x4' sheets they use for padding between pallets, so I might could get my chinnie wall to guard the nonchewables as well. I'm quickly falling in love with cardboard. Will post pics when the maze is built!