So I wanted to share my experience building a stand for a new 150 gallon tank I'm working on. I used the same method to build the one for my 80 gallon tank as well!
First step was to measure the new tank and decide what I wanted the dimensions of the stand to be. From here it was just a matter of playing around in Google SketchUp to design the new stand. Great tool that's free and easy to learn, make your mistakes in there before ordering anything!
In my experience 45 series 10mm slot extrusion is a great fit for stands from a price to performance standpoint. The website https://www.tnutz.com/ is where I have sourced the aluminum and accessories for my different projects. They cut everything to your specs exactly and ship in a timely manner.
It's somewhat time consuming to used the "inside corner gussets" and hammer bolts to connect everything, but it gives the stand great rigidity! I recommend buying additional hammer nuts and bolts off Amazon for attaching other accessories like the power strip pictured as they will be less expensive.
I'll update this post as I make progress on the build, and feel free to share any questions or feedback if you have experience building with aluminum extrusions as well!