The bolt in my toilet's handle broke so I needed to replace the whole system. @zzzy's handle, lever, and axle work, but I also needed a new bolt that would work with the existing nut. I modified @BPmakesthings's bolt for that. (https://www.printables.com/model/580625-toilet-flush-lever-repair-kit-straight-angled-amer). BP also has a nut available if yours needs to be replaced. I did not make a version of that, though, so you'd have to scale it and do some test prints.
I changed the axle pin shape from a triangle to a hexagon to give more options for mounting the handle.
Printing the axle horizontally led to a ton of post-processing, shaving it down so it would be (mostly) round. So I tried printing it vertically and that worked better. Requires supports and a brim, but those easily popped right off. I uploaded the CURA file for printing the axle.
I don't have any ASA or ABS (that would be better for toilet parts), so the handle and lever are PLA and the bolt and axel are PETG. If they break, I will just print more :)
Press fit should work or you can glue one side of the axle to a part (not both, in case you need to remove it), or try wrapping some teflon tape around the hex parts of the axle.
Glacier Bay tank #140-911
The author remixed this model.
Slightly modified zzzy's and BPmakesthings's models to work together on a Glacier Bay left-side-mount toilet flush handle.