I would build it out of melamine-coated particle board. It will be stronger, and you won't have to seal anything except for the joints where each piece of wood is connected to the other. You can get Aquarium sealant as well as the huge sheets of the melamine coated stuff at Home Depot. They will usually cut it for you for free, but if not, it's only $0.50 a cut anyway.

Here are a few links you can look at to build a better cage. I would heat it with a heat panel attached to the ceiling of the cage since flexxwatt or a heatpad won't go through it at all.

http://www.arbreptiles.com/cages/cages.shtml This one has a few different cages, as well as racks, incubators and whatnot. It seemed like a good source.

Here's another one with just one cage: http://strikingserpents.com/cage.html

That first cage just looks like junk... Sorry Ones made out of melamine will hold up better and will look better. For your male boa, I would make a 4x2x2, or maybe even a 4x30"x2 cage. I doubt he will need anything bigger, and 3 foot deep is a LONG way to reach inside for a snake. Wouldn't want you getting bit or anything if he decided to get rambunctious.

You "should" be able to get everything from Home Depot. I know the big sheets of melamine cost arouns $27 a sheet. The sealant cost $4 for a good sized tube(not those tiny tubes from the pet store). You can probably get the glass there, and cut to the dimensions you need it to be. The sliding glass tracks can be bought there, as well as the handles for the glass, and the display case lock/key. Should be fairly simple, just be sure to pre-drill your holes before you screw the screws in. I used 2" wood screws as well as wood glue. Just helps the joints be more secure.

I hope this has helped a bit, and let us know how the progress goes on your cage. I can't wait to build one myself. I bet it will look nice. Just take your time on it, don't rush, and it will turn out great.