Building a Chassis Dolly

I don't have the luxury of (or space for) a vehicle lift.
Many of these cars are assembled start to finish on jack stands... but building a dolly/trolley gives you so much more flexibility while assembling the car.
I wanted something sturdy, mobile, and elevated enough to save my back for the anticipated 1-year duration of the build. I hope this gives you ideas for your own project!
*Please watch to the end for IMPORTANT updates to the original design*