We made indoor aviary type cages using SS welded wire and anodized aluminum tubing for the frame.
You can see a picture here:
Play Cages
This is where I purchased the stainless steel welded wire.
Welded Stainless Wire Mesh
This is where I purchased the Anodized Aluminum Square Tubing and Connectors for the frames. On the fasteners page they have threaded inserts. We used those and made it so the panels can be screwed together just like regular cage sections do.
Brunner - Anodized Aluminum
I'm thinking of possibly doing a PVC frame with the SS Mesh for an outside enclosure.