A lot of the dimensions came from the limitations of the material I had on hand. A friend gave me a stack of 2x4s, and I processed them to get the most I could out of the boards for the top. So the thickness, length, and width were mostly dictated by that. I tried to maximize the size of the bench since I often work with large material. Case in point, first project was some sound panels that were the same size or larger than the top.

For the design, I watched a ton of videos and tried to pick out the best parts. It was important to me to have the legs flush with the edge of the top so I could work with material vertically ans clamp to the legs.

The bracing I commented on elsewhere, but I wanted some extra structure, some extra weight, and dog holes on the working side.

I didn't feel the need for fancy joinery, but I wanted the strength so I used half laps everywhere, which still turned out to be a challenge with the size of the parts.