These are spring-loaded clips for a bike bag, similar to ortlieb's style, for DIY bicycle panniers. I made it parametric and uploaded hooks ("hook" "latch") and bottom clips ("leaf") for different diameter rack tubing. The diameter in file name is finished printed size- so round up when you choose which size to print. This design works really well, but it is also complex. You need:

-m3 x 35mm SHCS for pivot
-m3 tap (optional)
-m5 x ??? for mounting holes. Bottom hole is countersunk for flat-head m5 screw.
-m5 tap if you want to use top mounting holes
-wire for spring. I used .6mm/.022” dia spring steel which is the right amount of spring tension. Wrapped (3) turns around a 4.5mm shaft to produce the spring. Leave the spring tails 4cm long or so, so you can assemble it. Once the ends are trimmed, it is VERY difficult to reassemble. There is room for variation in spring, use what you can find.
-paracord. The ends are threaded through the hook, and melted till the tip balls up. This secures the paracord in the counterbores on the inside of the hook.

The hooks and latches are printed on their sides. The m3 counterbore faces up on the hooks. The spring boss faces up on the latches. The leaf is printed with wide surface to the bed. Support material is only needed on the inside of the hook where the latch slides in. Added support blocker inside the tiny hole on Hook for spring.

For all this work, you get a really nice set of pannier clips for your DIY panniers. PLA is plenty strong. Design seems somewhat forgiving to different print settings/nozzle sizes. The latches have a travel limiter so you can actually carry heavy bags by the paracord release pull.