You could make your own...... but it's far easier to just buy an aquarium. Buy the largest aquarium you can. If you have to save up a little bit, then do so because you will fill it shortly.
Buy a sheet of light diffuser at Home Depot or Lowe's, and cut to the dimensions of your aquarium. Place pots in the bottom of your tank, or for a more time consuming alternative, make a support out of PVC. Sit the egg crate on top of this. This is called a false bottom and will be your reservoir. Go to Wal-mart or Home Depot or Lowes, and buy a shop light that is the same length as your aquarium. I recommend 48 inches. Regardless of what length you buy, don't buy one with fewer than four lamps. Of course, two shop lights that hold two lamps each is fine. If you can fit more over your aquarium, then by all means buy more. More is better.
Buy mylar and cover the sides of your terrarium with it. Don't use aluminum foil because it sucks compared to mylar.
You may turn your aquarium on it's side for more horizontal space, at the sacrifice of a false bottom.
I can not recommend Cephalotus to you if you're just starting out. If you want to grow highland plants with lowland plants, then your best bet it to make an intermediate setup. You will not be able to grow plants with stringent temperature requirements, however you will have a decent newbie selection. Personally, I recommend going lowland. It's easier to heat than it is to cool and most of the plants are very fast growing. Since you're in Oregon, you may have naturally highland conditions. If you do, then by all means go highland, but they aren't as fast.
If you have your heart set on an open-door terrarium, go buy an Exo-Terra terrarium. Even if you buy the largest available, you'll fill it up in no time.
By the way, get a small fan.
Here is mine:
Was it everything you imagined? lmao