I wanted to use the template as closely as possible, so I designed a shell with longitudinal ribs. Now to get the shape right
I started by laying a sheet of plywood on the floor and tracing it. There is very little else you can find that is more true and square than a sheet of plywood.
I moved it 4 feet, so I could get a 12' grid drawn.
I moved it a couple more times, ending up with a 6' x 12' grid, on 2' spacing.
I hope to build a tail for the truck and thought I could use the length.
Now I could arrange the sheet of plywood to minimize waste.
Using a printed image of the template, resized to suit my truck, I scaled it to get dimensions at stations, and transfer that onto the sheet. I pulled a tape and also made station lines on the angled plywood.
Now I have marks on the plywood that are 2' apart. I want to draw a smooth curve through these points. I have a fiberglass rod for network wiring, but a 10' stick of 1/2" CPVC pipe will work as well.
I started by clamping the rod at one end over a mark, then bent it across the next and the next, taking time to smooth the curve.
I cut the first one out very carefully with the sabre saw. Since the cut is so close to a rip with the grain, the saw wandered pretty badly.
I got a decent looking curve after a couple of attempts, then used that as a guide. Once again, the sabre saw would not track well.
I ended up setting my cordless circular saw to just barely go through the 3/8" ply, and used it instead.
4 finished curves.
I painted the headache rack with something close off the bomb can shelf.
Installed and bolted in solid.
I clamped a piece of 3/8" ply to the rack, and transfer marked it with a straight edge laid on the cab, and cut it out. It has 1/2" margin for the skin and construction method.
My box lids are one of the challenges. I have to make a door in each side of the shell so I can get into the boxes.
This also makes a big hole in the structure I have to work around.