Thanks Kallmond. It's actually a relatively small upholstery shop, with a total of 5 full time and 3 part time employees. I'm fortunate my boss lets me use the tools and shop for projects. I've built sub boxes and plenty of furniture in my time after work. This whole stand has been built with the table saw and miter saw.
Chris, I did not add any cross bracing (I'm assuming you mean like a cross brace from a top corner to opposite bottom corner). If i were building one for a large tank like a 150, I would either add cross braces or more top to bottom braces. The stand is a total of 49" long, so I didn't feel like it would be neccessary. There's no concern of twisting. I've screwed each joint in each direction possible, and with all the bracing, I couldn't imagine it twisting.
I'm not sure I built it conventionally either. I cut each piece and assembled them in sections. So 4 10" pieces, and 4 48" pieces. Then assembled two large rectangles, a top and bottom. I then added the center brace. Having the large staple gun was a huge help in keeping things square while trying to screw them. I was able to use 2" staples to hold the 10" braces inside the long pieces, then check for square and screw it.
Then I cut 4 31" pieces and 8 25" pieces. I marked each of the 31" long pieces at 3.5" (width of a 2x4) and attached a 25" piece to it. After doing this to all 4, i turned them on the side, and simply lined up the second 25" piece and screwed it in. I had no need for a square, because I knew my top and bottom rectangles were square, and I knew each upright was now square. You can see this in my first pic. Checking to be sure they were pushed all the way to the corner and touching the bottom 2x4 frame, it kept them square. It's hard to explain, I should have taken more pics.