I have a couple cages made from wire shelving. I love them.
However, I do not use wire shelving for the flooring. I don't think it's good for their feet. I make the flooring out of 1/2" x 1" wire with supports every 24" (so really just 2 supports)
PICS HERE
The cages are held together with hog rings, simple, very strong, cheap on Amazon.
Only drawback I've found is that I like the rabbits to be able to stretch their backs & have more room, so I've added a 2nd story made from an old bird cage. But without the height, they'd still be okay, esp for grow-outs, etc.
I'll post a couple pics of the 'townhouses' later.