I needed a dog poop bag to fit the smaller Flexi Leash sizes, like this one here, but models like those in the parent didn't quite fit (were too big).
After getting frustrated and printing a few different ones, I realized it would be best to modify one of the designs out there. The key was slightly shrinking the part that goes into the Flexi leash box slot. It appears to be slightly smaller on these smaller size leashes. I printed mine in PLA and PETG.
I hope this modification/remix from the parent helps people out who were stuck like me!
I only changed the body of the container in this remix, so the cap design from the parent is the same should fit just fine! I included it here for completeness, however, to make it easy to download one working zip collection.