Found a slim plastic clipboard case at Staples that fits a few of the things I often carry around in my bike bags (notebooks, etc). Modeled these hooks to turn the case into a compact clamshell saddlebag.
I've made the Onshape document public as Clipboard Case Pannier Hook.
I printed a pair of the
doxboxclip.stl models to replace the red latch piece. It fits more securely - I was a bit worried about the original clasp popping loose.
Printed with 0.3 mm layers, 4 perimeters, and 20% rectilinear infille. No supports. To print a symmetrical pair, use your slicing software to flip one instance before printing.
"Vitamins": Attached to the case with some 5x12 mm bolts, nuts, and washers I had lying around. A small bungee cord loops under tabs on the bottom of my bike rack and connects to the hooks to keep them under tension so the case doesn't bounce around too much.