At Thermalwrong's suggestion, I raised the edges of the AT I/O plate a millimeter, to make them more flexible and hopefully work better with PLA.
I did not make the grips smaller though, since there's some I/O plate hole size variance between cases. It's easy enough to sand them down if necessary. Sanding them also gives the additional benefit of a smoother surface without layer ridges, which will make installation easier.
It'll of course also work with other materials. Should be a little bit easier to install than the original version, it might not sit as safely in the case due to the increased flexibility though.
If you print this, please tell me how it worked, and if further adjustments are necessary 😀
Pics with comparison + .STL file attached.