Hi, I don't keep any Uro's so don't have species specific info
but, have a fair amount of cage and cabinet experience 
Go Modular if you can, that way you can add/expand/rearrange as future changes happen. You know the future will change
One leads to two which leads to even more blah blah blah
Before you design/buy/build anything figure out your needs first! Including but not limited to:
Floor size (Uro's are ground dwellers so arboreal is not an issue....right?)
Heating, belly heat, RHP, basking spot etc.
Temp controls? Thermostat, what kind, where to put, where to place probe etc.
Lighting, will need UVB?
Cage access? How do you want to access cage, top lid means no stacking, front door means litter dam and maybe less viewing area, side door means larger viewing area but then you can't stack side by side cages etc. etc.
Since you're building it yourself, where will it go, that may limit your options and may also help decide sizing.
Here's an example of a modular stack, these are for Brazilian Rainbow Boas but you get the idea. Each level is a seperate cage. The center divider is removable if need be (is sealed with caulk so would be a little bit of work but do-able). These have a lot of cool features like fully formica'd interiors, external connecting tubes for breeding, keyed alike doors etc.

I and others here would be happy to help with design, just give us some specs!
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Thanks,
Dave Colling

www.rainbows-r-us-reptiles.com
0.1 Wife (WC)
0.2 kids (CBB, selectively bred from good stock)
LOL, to many snakes to list, last count:
11.24 BRB
10.16 BCI
And those are only the breeders 
lots.lots.lots feeder mice and rats 