Lattice in Solid — Fills a Solid with a lattice: the cell, picked here or wired, is tiled over a box, cylinder or sphere grid or a wired cell grid, cells that cannot touch the Solid are skipped, and with Trim on the lattice is cut flush at its surface.
Skin — Gives a filled part a closed outer skin: a wall of the given thickness inside the part's surface, joined to the infill (rounded where Blend is above 0) and cut with the part, so the outside stays where the part's surface is.