My newest creation - a "maze" for the rats made of 3" PVC pipe with pre-cut holes. I found it at Home Depot for about $4/10 ft. I also got the black tubing for the same price. A $20 hacksaw to cut everything down, and a $4 sink organizer from walmart and there you have it. (Well, I decided to get fancy and buy a bunch of PVC elbows which made it more expensive. They're $3-$4 each.)

The sink organizer already had a hole in the center to allow food debris to go down into the drain of the sink. It had vertical bars to hold plates upright while in the sink. We took the lower door off the rat cage and attached the sink organizer to it with zipties, then attached the tubing to the organizer with more zipties. Everything else snapped together but we ducttaped just in case.

An over-all view:


Side-view:


Front-view:


And the turn-around to go back to the cage:


It goes up and over their cage, along an un-used tv center behind the cage, down and along the screen windows before finally turning around to go back. We still have a lot of tubing and pipes left over (another 10 feet!) so we're going to save it and better the tunnels when we move. The apartment is being rented to us by someone right now. All the CRAP you see in the photos is their stuff. We're not allowed to move it so we have to build and work around it. I have now become an expert at getting the most out of the least possible space. (Comes in handy when loading the dishwasher... )You may have even noticed our little container garden going on out there.

The rats seem to like it.