Since you say wood working etc. is not something that comes naturally to you I thought I should ask you a pretty basic question. I only ask this since I've run into this problem a lot over the years of consulting people on cage design.
My question is will you be able to fit this cage in and out of your home? If the answer is no, you may have to consider different dimensions (probably cages not as tall) or assemble and finish the cage in your home.
The latter comes with it's own set of problems.
I've worked yellow anacondas and think you could get away with a much smaller cage. But a tegu probably does need a large area so it's probably not a big deal to build two cages with the same footprint.
An easy way to check this is to get a big piece of cardboard and cut it to the dimensions of the cage you want. In your case you'd want it to be 3' x 3', or the dimensions of one of your sides. For a cage this big you'll almost certainly want to turn it upright when you move it so that's why you use the dimension of one of the sides.
Actually, you'll want to go slightly bigger than 3'x3' just to be safe.
Then slide this piece of cardboard around corners, through doors etc. and see if it will fit.
If it barely misses you can then trim down the cardboard until it fits. Whether you end up subtracting this from the width or height of the cage is up to you. If you do end up subtracting from the floor area you can make some of it up by making the cage as long as the height of a doorway (actually slightly shorter to be safe).
For the species you keep I'd prefer to take a bit away from the height of the cage rather than the width.
Lastly, you might consider going to more of a specialty lumber yard or cabinet making shop to buy the wood for your project. I say this because Home Depot does not guarantee the accuracy of the cuts from their panel saws. I've had good luck and bad luck with the squareness of their cuts. Fortunately I'm always prepared to take the cut pieces home and square them up myself. But that's something you probably don't want to deal with since you are not yet a confident cage builder.
******************
When it comes to wood working and planning a cage, a rock could out think me.
I just have no experience in it. At all. But I'm sure I can get help, heh.
So I was curious: Is anyone around here willing to give me a copy of plans for a 6 (minimum) long cage, 3 (minimum) wide, and 3 foot tall cage?
Or better yet, some sort of double cage where I could have two cages of that size stacked?
They need to be fairly water resistant and able to hold humidity fairly well.
And most of all, easy to build with Home Depot type stuff. Nothing too fancy. At this point, I'm not craving something really fancy looking.
In case you were wondering, the animals that are going to be enclosed are Columbian B&W Tegu and a Male Yellow Anaconda. (I get bugged a bit by the Anaconda thing, so I'll say male yellows don't get nearly as large as the rest of the Anacondas.)
--------------------------------------------------------------------------------