Apparently, I have become neighborhood famous; in the couple of hours I was out in the shop today, I gave two nickel tours of the frame and the assembly process.
But today, I wanted to detail the process I am using to attach an aluminum panel to the frame.
First, the panel is held against the frame with clamps. I do a lot of eyeballing and measuring and feeling until I feel like it's appropriately lined up, and I use blue tape and Sharpie marks to make some references.
Then, from the other side, I make lines outlining all of the tubes it will rest against.
On the bench, I do a lot of layout with rulers and Sharpies to figure out the lines I will put rivets along, to hold the panel firmly to the tubes.
Here's a closer view of my layout lines.
This is a marking tool I made from a cheap aluminum framing square. Once side has holes on 2" centers; the other side is 3" centers. I'll use this to mark out the rivet spacing. In this case, because the panel is being mounted to the frame, I'm using 3" spacing.
I did not get the whole panel marked for rivet locations today - I'll finish it up tomorrow, I hope. I think it needs a little revision anyway, so that things come out a little nicer than they currently are.