I found those photo's on the website Kevin tried to link to. That looks like it was professionally made. I've no experience in building doors like that, but might be able to get doors like that from Home Depot/Lowes etc.
I found these pics in a thread at the reef2reef forums. If you trace back to that thread, you'll see the stand being delivered along with the tank. It's interesting to see the fork lift they used to move the tank onto the stand.