4" Drainage Tubing Home Improvement Store - $2.00 (for 10') RattyRat's Review: This black tubing makes fantastic tunnels for rats. It's cheap, durable, easy to clean. It's the best thing you can buy. They come in 10' sections which you can leave as one really long tunnel, or cut up into all sorts of shorter tunnels. You can even wire a bunch together to form fun toys like the one pictured above.