Ingenious use of recycled materials and a great basic design! I, too, like the idea of a tunnel and would appreciate your telling us how you dismantle it to clean it up inside when necessary -- is it composed of pieces that come apart?
SInce it's only beem operating for a month or so, I haven't had to clean it yet. I thought long and hard about making it so I could take it apart to get a chook out or clean it, but in the end just nailed it all together.
I'm not too worried about it getting dirty as the rain should keep tha in check. Having a chook stuck in there is a bit of a concern, but since I know how it went together, I could get it apart pretty quickly too.
In hindsight it would probably best be done with a lid that comes off, but by that stage I wanted to finish so badly I decided that sort of modification could wait.