Started by cutting a 900mm long, 3" wide strip of .025 6061-T6, placing 1/4" 3" wood to protect edges. Banded it together and squashed it the the 58mm blocks by hand.
Removed the band and marked center of bend on the outside of the bend. Cut two strips of the strapping, one 411mm and one 407mm. Marked and trimmed the test piece to these dimensions and put in one #30 hole for the bottom cleco 10mm from the edge.
Image 3) Clecoed the one point on the bottom and handi clamped the strip around one of the ribs. This fits great and I have about 5mm extra on the top side.
Thoughts: Should have done this to begin with. Oh well, this is a learning experience.