Part 2: Then I cut out the filler box opening and bent up the flanges using the hand seamer. Then drilled the filler box to the firewall. Then drilled the filler box forward side to the filler box, but wasn't happy with how the upper flange of that aligned with the box side flange - the little doubler that connects these would bridge almost 1/8" height difference between the two. So I made another box forward side. This one turned out a little too tall, so I put its lower flange below the filler box instead of above it. That made the doubler work out just right. Then took everything apart and cut the slots for the engine mount. Then test fit the firewall by itself and trimmed near the engine mount angles until the bare SST fit to the rest of the firewall. Then clecoed the windshield strap in place and trimmed it until it fit between the forward fuselage side panels. Got it all done exept for the deburring, dimpling, and riveting. Drilling the SST isn't easy - I burned up two drill bits, broke a third, and the 12" drill bit should be retired, but I got it done. Dipped in WD40 for cooling/lube between each hole, but I'd made the details before I got the hint to just drill to #30 in the first place, so I did all this with #40's first - running through with #30 is easy after this.
Fuel filler box.
Forward side that I remade to match at the upper flange better.
