Inspired by podkin's post, I picked up some stuff at the thrift store and talked with my husband about it. Today he surprised me by whipping this up from the items I bought last night and some extra plywood we had leftover from building Oswald's cage. So far, he doesn't know what to think. He doesn't seem to like the ramp, so we are probably taking that off, and he hasn't gone inside of it yet. I hope he ends up liking it though. I think it turned out nice. He looked online for some ideas, that's where the inspiration for the pinecone "wall art" came from.
Here he is checking it out, not sure what to think.
The round pieces are the leftovers from what my husband drilled out. Pinecones are stuck in the wall 
I still need to throw a towel or something in the basket.
Closeup of the pinecone "wall art"