Wow! That was a pretty awesome link. I'm in the midst of making my first chinchilla cage now (I'll have pictures soon!). There have been somethings that I've learned that you might find helpful:
Making the whole cage out of melamine or plexiglass isn't recommended because it can trap the heat. The cage I'm making has a melamine back, but the rest is made if pine beams that measure 7/8" X 1 1/2" and it's plenty strong enough.
Also making the shelves out of melamine I don't think is recommended since it is a kind of plastic. I'm going to make my shelves out of cheap 1" X 12" pine boards and screw them in so that they can be easily replaced when they inevitably get destroyed.
Also I'm going to try keeping the chinchillas from attacking the cage by using cornerbead on the exposed wood. It's pretty cheap and I'm sure it'll be effective.
As for size, the cage I'm building is 2x3x4 and I'll be keeping 2 chinchillas in there. From what I hear, that's going to be plenty big enough.
Be prepared to invest some time in the plan and cage. I've been working on mine for about a week, but I'm almost done. It'll be so worth it in the end. It's only going to cost me about $50!!!