Didn't get as far as I expected but did make some progress. I started with mounting the drawer and counter slides into the box frame. Here's the doodads I made to mount to the slides and then weld into the frame of the box.
Then I made some frames out of angle and welded in expanded metal.
Next I skinned the front and back with .080" aluminum diamond plate. For this I glued it to the frame with windshield urethane and then riveted it with aluminum rivets.
I'm doing it this way because tig welding is beyond my skill set.
Next, I'll skin the ends, mount the doors, lights and switches and then put the top on.