I have built many wooden stands over several decades, dimensional lumber, plywood. The only suggestions I have are (1) DO NOT use chip board, particle board, OSB, etc. It will get wet, and it will fail. (2) Static load strength is important, but seldom do people build stands that aren't strong enough in this way... Lateral strength, to stand up to wracking, twisting, or swaying, these are equally important, and much more often overlooked.
Before you go too far down this path, my last stand was done in steel. I'm as happy as I can be about it, and it was not expensive. I believe I saved money over buying the materials I was going to buy to make a cabinet grade plywood stand with solid trim. DON'T call an aquarium company for a steel stand, they're prices, in my experience, are ridiculous.
Here's what I did... Called the local steel vendor, and asked the guy that answered the phone if he could suggest a small fab shop for a small steel project. They did. I called that shop, and provided him with a drawing of what I wanted, specified 11 gauge 1.5" square steel, and told him I wanted it left in mill scale finish. He quoted me a price. I then called a local powder coat company, and got a quote for sand blasting the mill scale off and powder coating it gloss black.
Reasonable price, exceedingly strong, as much open space as you're ever going to get, easy to 'finish out' to match your decor, and should last far longer than I'm going to be around to need it.
As it came from the powder coat company: