Create a solid hatching, arbitrarily something like a grid with 1mm thick lines at 3mm spacing, so a linear array of plates added to a copy rotated 90 degrees or similar. Make a copy of the outer shell of your model, which has got to be a filled solid, and intersect it with the grid array to provide the fill, then add that to a shell of the outer surface, while your original .stl, .obj, .3mf, whatever is probably solid fill, so you'll have to add that to your workflow. Bear in mind that the standard infill also supports overhangs of the upper surface, if your custom fill doesn't accommodate that, you might get sag failures.

Edited by user Tuesday, November 15, 2022 6:50:18 PM(UTC)  | Reason: Not specified