My husband is actually finishing a stand for a 75 today - we had picked up a setup off Craigslist but the stand was pressboard and had gotten moisture on it while in storage (have verified this story from seller by checking tank for leaks) so it was crumbling and unusable. I'll get pictures of what he ends up with, but we based his plans off this: http://www.tropicalfishkeeping.com/saltwater-aquariums/75-gal-stand-93328/
Building a stand can mean a lot of things to a lot of different people.
As you search the web, you will see mostly two types of stands.
One is made with a 2x4 frame. Some people just leave it open, and others "skin" the frame with some type of plywood veneer.
The other type is constructed mostly with 1x4 and 1x6 hard wood lumber.
I recently built mine for a 120 gallon. Here is the link detailing my experience: