Internal fillets in transition from solid to sparse infill
Most 3D printer users know that the print is weaker in the z-direction and also know that sharp corners should have a fillet to reduce stress concentrations.
However, the print will always have sharp corners in the z-direction internally if using sparse infill.
It could be nice to have a setting to have additional walls at the bottom and top layers of sparse infill so that an internal fillet is created where a bottom or top solid infill meets the region with sparse infill.
I can see how this can be challenging to program if there's multiple levels of top layers, like a stair shape and also if theres a wall with a shallow slope so it has a bit of solid infill in every layer but if this was solved so that there's a minimum radius at all internal corners in the z-direction, I think it could add strength and let us make better use of sparse infill for parts that are loaded.
The problem is that Slicer treats each layer individually, it doesnt pre-process the entire model which would be needed to make those sort of decisions and frankly its probably going to be difficult even if it did so.
Walls with slopes already have settings to handle this, 'Ensure vertical shell thickness' for one and 'Extra perimeters if needed'.
If you would really like to see this then you would need to open a request over on github. This is mainly a user to use forum and while the devs do occasionally pop in here all bug reports and feature requests need to be posted over there where they can get tracked and issued a ref number. https://github.com/prusa3d/PrusaSlicer/issues