Here's a thread to share pictures of my cabinet build for a unique setup (I haven't seen it before, but I haven't looked that hard either). I built this whole thing using only a few tools that I think most folks have. It only took a few hours to do.
Materials: part of a 4'x8' sheet of 1/2" thick oak veneer plywood. Four 1"x4"x8' premium SPF boards. A fistful of 1" and 1-5/8" screws. Two scraps of plywood triangles.
I intend to place a 20L tank on top and a 29 tank on the bottom. I have two 20Ls in the picture for reference. Also, I will have a sump or refugium inside the cabinet to add volume for a healthy system. This third tank will probably be a bucket or plastic tub -- something cheap since it is hidden. All these tanks will cascade from one to the next, and a sump will lift water back to the top.
I said I only used some basic tools, so I'll list them here: circular saw for the plywood, straight edge with the circular saw, hand saw, hand miter saw, miter block, cordless screwdriver, carpenter's square, tape measure, and a pencil. When I picked up the plywood at the Home Depot, I had them make a few cuts to the major dimensions I needed. This saved me a lot of time. Lining up the straight edge and making the cuts with the circular saw took about an hour and a half to do since I was being very careful to make my cuts accurately. Despite my extra care, I still screwed up a couple cuts a little. You'd never know if I didn't tell you. I used the miter block and hand tools to cut the 1x4 because I live in an apartment and don't want to disturb the neighbors too much with the noise of the circular saw. Plus, I don't have to to to my garage to use a handsaw.
I'm disappointed by the exposed edge of the plywood; it detracts a lot from the oak veneer. I knew it was going to happen, but I was limited by the tools I had. I'll come back later and redo the edges when I get access to a router and other tools to add a solid oak edge band. I didn't use any glue during the assembly because I expected to take it apart later for this rework job. I'm a bit of a perfectionist, but I think it is OK as it is. Have you been to a Chipotle and seen all the exposed edges on their birch veneer plywood designs?
One thing I notice with folks' DIY stands is that they overbuild them. Just peek inside the commercial stands and realize that you need a lot less structure than you think. My design depends on the strength of the plywood and 1x4s. Although a stand built with 4x4s and other big members will be more rigid, it would be heavier and cost more for materials. This wooden structure only weighs 30 lbs or so. I can stand on it, so it is plenty strong and rigid.
I have zero access to the inside of this stand from the front or side, but the back is open. I'm going to have to think hard about how I expect to service any of the equipment inside if I place it against the wall...
I'll start a tank journal for this project also. I'll post a link in a while, so head on over there for more info on what I'm doing.