Cabinet: I wanted to try something other than the standard "2x4 frame plus plywood skin" approach. I used 3/4" cherry veneered plywood, solid cherry for the doors, base, and top, and curly maple for the trim. The beam across the top front is two pieces of 3/4" wood with a 1/8" steel bar sandwiched between them. This was utter overkill, but I didn't want the top beam to deflect downwards and interfere with the inset doors. And steel is way cheaper than cherry. The whole thing is a rat's nest of construction techniques--I used Kreg screws, glue, nails etc. depending on the day and my mood.
The cabinet sits on four heavy-duty leveling feet, which in turn will sit on 4"x4"x1/2" pieces of wood to distribute the load. I wanted to use leveling feet so that I could level the stand any time even after filling it. (I hate the look of an uneven water line in a rimless tank, and my floors are ancient and likely to sag and settle over time.) But leveling feet are ugly. So I built a false plinth subassembly that surrounds the base of the tank. The plinth hides the feet and makes the whole thing look a little nicer. It slides up and down over the cabinet with some coaxing.
Although the Oceanic tank has no top rim, it does have a bottom plastic rim. I didn't want to let that show, so I built a top frame subassembly to hide it. The top frame slides down over the tank once the tank is on the stand. I cut a profile into it to minimize the gap between the frame and the tank. I can remove it if necessary in case I get any major spills down the sides of the glass, but it's tight enough that I doubt that will be a big issue.