>>I basically need a 4ft wide by 2ft tall by 2 ft deep cage, and another one that is only 18in tall.
A few comments on your dimensions.
First, consider making the cages just a bit longer. I'd say either 49.5" or 50.5". That will make it much easier to fit 4' flourescent light fixtures into the cages. I realize that mercury vapor bulbs are so good enough nowadays that these fixtures are not necessarily needed but you never know when you might want or need to use one.
The above two length options are easy to achieve at no extra cost. For a 49.5" long cage you simply have a 4' piece of plywood fit between the two, 3/4" sides giving a total length of 49.5".
For the 50.5" length you would use a sheet of melamine (cross-cut) between the 3/4" plywood sides. From your design it appears that all of the horizontal pieces would be hidden so using melamine would not be a problem.
Melamine is 49" wide compared to plywood at 48".
Regarding the height of the second cage, is the 18" the height of the area where the lizards will be contained or does it include the hidden light area?
I ask because generally 14" is the minimum height I recommend for the viewing area of a cage that is designed to be nice. When the height of the viewing area of a cage is half the "depth" of a cage it just is not as fancy of an appearance. I'll post a picture of my Bearded Dragon cage in another post. It has a 14" tall viewing area.
Lastly, try to get the total height to under 80" with the casters. You really want this thing to fit under door openings. Trust me on this.
>>How much ventilation is needed?
With the heat required by uromastyx, probably not very much. Any residual moisture will be dried out by the heating elements.
Still, I like to provide a lot of air flow for most any species of reptile.
>>How much ambient heat will rise into the top cage? Do the area where the lights will reside need some sort of insulation?
Some heat will rise into the cage above. You could try what I did with my Bearded Cage. Attach a piece of foil-covered, styrene insulation to the floor of the cage. The cover the styrene with a scrap piece of vinyl floor or some other type of plastic. The foil will help block radiant heat, the styrene will slow down the rising of conductive/convective heat.
>>How do I incorporate temperature controls into the design?
I assume you'll be using mercury vapor bulbs for the cages. I tend to recommend the externally ballasted variety which don't get nearly as hot as self-ballasted. And they last longer.
So you'll need another heat source, likely a ceramic heat emitter. Simply run that through a dimmer and/or thermostat. If both CHE's were run through dimmers and then through a thermostat you could get away with one thermostat for both cages. Without a dimmer the above cage will likely get hotter, especially since it's so short.
>>I would like to house both the lizards for under $1000.
Some ways to make it cheaper:
1) Use cross-cut melamine for all of the flat, horizontal pieces. The main disadvantage of this is that you won't be able to use cross cuts for the front of the cage, meaning your grain will run sideways instead of up and down. But I would use birch plywood anyways with the mahogany stain so the grain will barely be visible anyways.
2) Use sliding doors instead of hinged doors, glass instead of acrylic. Sliding doors also tend to give the cage a more open look which I prefer. The same look can be achieved with a frameless door but those tend to be more expensive.
3) Have the access to the lights be from the back. If you really want it from the front, use some stained wood attached with cabinet magnets instead of a hinged, tinted glass door.
Another advantage of having the access from the back is that solid pieces of plywood can stretch across the front of the cage, providing a lot more stability around the doors - the area that needs it most.
4) Same thing with the drawer area. Either have no door at all and have nice baskets full of supplies or simply attach a "face" to the opening with magnets.
I'd strongly consider losing the drawer area if possible. It will make the total height shorter and also allow for large pieces of solid wood or plywood to "frame" the front of the unit. This will make the door openings much more rigid and square.
5) Don't buy any fancy ventilation ports. Simply have the ventilation out of the back of the cage.
6) This won't save that much money, but use regular instead of locking casters. With the kick plate you won't be able to access the locking mechanisms anyways.
I'll upload some pictures in individual posts.
-----
1.1 Gonyosoma oxycephala - (Silver/Yellow)
3.4 Gonyosoma oxycephala - (Green)
2.1 Gonyosoma janseni - (Black)
