Skribbles,
I am attaching the site that I put up when I made a new cage.
One comment I would like to make though is that Uromastyx are not necessarily social animals. I agree that from a human standpoint it seems cruel to keep them alone, but as we have seen time and again groupings of Uros can sometimes turn very aggressive even after they have been together for some time. So, if you decide to add more Uros, make sure that you have seperate housing set up for them as well, in case they have to be seperated. 
As to size, I had my full-grown mali in a 4 x 2 x 2 tank, and I would not really have wanted it any smaller. Multiplying that for 2-3 uros and that is a big cage! lol.
Good Luck on your habitat building!
Elizabeth

http://web.ics.purdue.edu/~echarris/archcage/
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1.0 Mali Uro Archimedes (May he rest in peace)
0.0.1 Egyptian Uro Zuberi Mosca Khu (Mosca)
0.0 Fish
0.1 Sulcata Minnie
1.1 Iguanas Flik and Loki
0.1 Newfoundland Jasmine (RIP)
0.1 Feline Winter
Indiana & Wisconsin