The basics of the bench are:
Length: 9 feet (against the wall), 7 feet (against the work edge)
Width: 2 feet (24 inches)
Simply 2x4 framing, 4x4 supports and 3/4" in thick MDF as the surface
Also included was a pegboard wall measuring 8 feet wide for tool storage
As you'll see, I didn't follow my plan exactly. I didn't use diagonal braces and only used two legs. The fastening to the wall on the two sides provided more support than I thought. The workbench can easily support all the weight anyone could throw on it.
Step 1: Preparation of the installation space
The garage corner contained a central vac unit which limited the width of the bench, and I also wanted to "notch" the rightmost corner to prevent body contact when moving around the cars. Running into sharp corners is NOT fun.
1. Measured a level line at 30" above the garage slab lip. Since the garage floor is sloped, this lip gave a better starting place to measure from. The level line is marked in red.
2. I chalk lined the garage floor to get a good idea of the space I would be taking up and to see if the car would hit when pulled in.