I found this posted here - https://www.thingiverse.com/thing:2066610 - but I am pretty sure that this is actually the same design posted here - https://www.thingiverse.com/thing:896665 - two years ago. In any event, I found several issues. One, the lip around the bottom was too flimsy - it detached very easily from the rest of the case with little force. This, too, was thickened and the angle of the overhang was increased to add additional support . Secondly, the battery "clip" exhibited the same flimsiness. This, too, was thickened to add additional support. Thirdly, the top right-hand screw hole was enlarged and attached to the case just like the other two for additional support. Finally, with the battery endstop in it's current position, the battery is unable to drop down into the holder with the thick, hard plastic connector (as opposed to the thin connector used on most 9v battery equipment) made into some testers. This was moved 4mm. This provides a snug fit without having to break that tab.
For those whom the other cases work fine, this offers no reason to change. For those who have issues with the original(s), perhaps this may help.