I just finished building a new play cage for my gliders (I HATE the tent!) It is 3 foot by 6 foot by 6 foot tall. It is made out of pvc pipe and plastic hardware cloth (found at home depot) It has a plexi glass door on it. It is made into panels and the panels are zip tied together so I can simply snip the zip ties and carry the panels outside to wash it. (I understand there are resuable zip ties out there, I just need to find some) It has melamine (shower surround) for the floor.
This whole huge cage cost me right about $130 to make. But the down side is...it is so big, it will probably cost me another $300 to fill with toys!
I'm attaching a picture of it. I have directions of how I built it in the works but I still have to do up the direction of how I did the door. If you want the directions to it, send me a pm with your email addy and I'll send it to you.
Oh, and this design could easily be made into a 3 foot by 3 foot by 6 foot tall cage. You can also use pvc coated metal wire for it instead of the plastic hardware cloth. (I'm lucky and don't have any chewers so the plastic works well for me)