I didn't glue anything, I'd call it more of a "rack" than a cage -- that's probably why it took me sooooo long to arrange everything in the tank to not only create the shapes I wanted but also hide the PVC. Basically, you're just stacking rock like you always would, but with a big hole underneath and behind it.
I've also seen (can't remember the member) PVC racks plumbed to a pump, and thus with flow shooting out from under the aquascape. No way any detritus collects anywhere he can't reach it. Now THAT'S cool.
