A Tale of Welding Woe
I went next door to the shop to do the welding about 1:30, with the

pile of parts
Bill, the guy who runs the shop, had said he'd help me get set up and help me if I got stuck. Instead,

he welded the whole thing for me.
Unfortunately, this turned out to be a very frustrating project. The plan was to TIG ( aka heliarc or SMAW) weld the face welds, because it is a cleaner, neater looking weld, and then MIG (aka wire welding or GMAW) weld the vertical joints for strength (and because MIG is fast and easy). We got some of the welding on the center frame done and then we had to patch up the gas line to the TIG torch. We did a few more welds, and we had to disassemble and clean the torch head because it wasn't flowing gas properly. Eventually, we abandoned the TIG torch completely and used the MIG for everything, which meant more grinding later, but less frustration because it was working.
Then we ran out of wire.
A search through the store room yielded a spool of flux-cored wire, which we used because it was all that was there, but the flux makes for messier welds (they splatter). Since I was going to be grinding welds anyway, this didn't matter much.

Eventually, we finished the frame
and I took it back to my building, and then down to my shop for grinding.

One last gratuitous grinder pic
Next thing to make are the wheel brackets.