You have allot to consider. Ventilation, heat, humidity, temp gradient, water dish, pool or not, if so-drainage and filling of pool, esthetics, hide box, growth of snake (size), security, ease of cleaning, etc. As far as close to their habitat, a burm will trash a cage and move anything not bolted down. They will also crap on everything so anything not flat will e a pain in the rear to clean and you'll get sick of it real quick. I really do not think it's practicle to make a cage for a small or juvenille burm. At least not one you would be proud to display. I've built 3 cages (2 for burm, 1 for balls). Each time I built a cage for my burm, he was to big by the time I got it finished. This last cage cost over $600 and at least 40-50 hours to build and I know you can buy a simple cage for allot less. His cage is really nice but he needs something bigger. I am going to build my final cage when I move to Michigan. It will take up a nice piece of real estate in my house but it will blend into the walls. Roughly 12 feet long, 4-5 feet deep and 6 feet tall (many levels for gradient and so I can get in to clean). It will take allot of money and then I will have this awsome cage (the one he's in now) taking up room in my house. I don't think you would get enough profit from building custom cages to make it worth your time and skill. Not to mention shipping something big enough for a large burm. Unless you live somewhere with a local market for these cages.
That is a really cool idea you have and would look awesome. I had the same idea but would not be able to build something into someones house due to liscencing. But all of the cages would be for large adult snakes and lizards. I have thought of everything you have mentioned and have an idea for all of them. I do not want to get into any grave details due to the possibility of my idea being stolen, but my burm is in need a of a new cage. So my functional model should be made soon. I have a few people interested in working on my idea w/ me, so i have people to deliver and put the cage together at the customers house. The biggest cages i have found are by Cages by Design and they are way to expensive for what they offer and my burm has escaped from that cage many of times. All in all, im not to happy w/ it. Maybe i have asked for advise to soon, but i will have a pic of one of the models when i am finished. Good luck on on your built in cage!