We order our wire from Klubertanz in Wisconson. You can view their catalog online by clicking on their name.
Hubby makes a double row of cages using two 14' lengths of 1" x 1/2" by 30" back to back, laid flat. Where these make a seam you attach a length of 18" x 1"x 2" with babysaver wire (4' deep) at the bottom to form a common back (cut in whatever length you are working with; we did 14' sections to make a double 7 hole run.) The sides, made from 1"x2"x 18" with babysaver wire at the one edge, are cut 30" front to back. The front wire is one piece, from 1"x2"x 24" bent at an angle with 14" being on the slant and 10" the very front.
Slant front has a hole cut out of 10"x16". The doors then are 14' long by 20" wide, hinged at the topseam, so they can lay back over the pen, and covering the hole and overlapping the sides of the opening, fastened with a spring fastener on the edge toward you. The top is 36" wide and covers both back to back cages ; each cage top being 18" front to back. Our cages are hung from the ceiling with fencing wire (can't remember the gage)
Now..... I add a disclaimer; Any information given here-in is correct to the best of my knowledge, however I will not be responsible for any mis-information. In other words, make sure to do your own math :)
I hope this post is helpful to those who are looking to build a rabbitry of more than hobby size..