I've built several aquarium stands and tables. They're easy.

I build a square that is the right size for the tank/enclosure, then a second indentical one to be the base. So you have a top and base square of 2x4s. Then you put in at least 4 and up to 6 uprights, fastening the bottom of each to the base and the upper of each to the top. If needed, you can add in a diagonal board on the back to help steady everything, but with tanks up to 75Gallons of salt water, I never did.

Wish I had pictures.