You might wanna scroll down this page, or go to page two of this board to find a topic just like yours.
You obviously want to make an enclosure that will last you in the long run, which means saving money that would be spent in another one in the future.
6 feet long, 4 deep, and 6 high are the basics. If you can do more, especially in the length and height, even better.
The true ideal is 7 long, 8 high, 5 deep.
Depending on where you live, you can build an outdoor one to enjoy all year long, or an indoor one. Or, one that can be moved on wheels in and out. However, it will not have to be made of glass, since a glass cage outside cooks an animal.
Ok... I don't have any exact plans for you, but often plywood is the choice for the back wall. The perimeter can be done using 2x4's or similar. The sides can be glass, and the front can be wire mesh or glass. It would be great if the front has a sliding door for quick easy access as well.
Some use showers in an unused guest or second bathroom, however they often tend to be a tad narrow. The tiles and drainage do make cleaning a snap!
Substrate is another issue. That fake-grass-like carpeting can be cut into squares, like tiles, and be easily removed, washed/sanitized, and replaced back in. Keep spares in between cleanings. It looks good.
Make the cage functional, visually appealing, and correct for the animal: climbing areas, hiding areas, cooling areas, basking areas, feeding, drinking, etc.
Hatfield's book has an excellent example. CagesbyDesing.com has models you can try to copy yourself.
Skim around this board and I'm sure you'll find plenty of other info. Good luck!
-IJ