Unicycle Saddle Bag Hoops
thingiverse
There is now a V2 of this idea, designed to also work for bags that are designed to strap onto seat rails. See here: https://www.thingiverse.com/thing:4932460 A simple saddle bag hoop designed to be attached to the bolts that hold on a unicycle saddle bumper. Designed to be printed on their back (hoop flat to the printer bed) so layer adhesion is less of an issue. I wouldn't go trying to hang multiple KG of bag off them and ride off-road with it, but they seem decently strong just printed in PLA so should be perfectly good enough for a small tools/emergency bag. The base section is 2.5mm, so depending on your saddle bolt length you may need new longer bolts to attach the hoops.
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