Sorry if this question was asked before. Im new to designing and ordering pcbs and i have a question. I ordered a pcb online and got an email from the manufacturer that i should redesign an outline as a hollow one instead of a solid one
The normal way for KiCad is to draw lines (rectangles, arcs, etc) on the Edge.Cuts layers. Together all these graphic items must form a closed loop, i.e. the endpoint of one item must coincide with the starting point of the next, and this is easiest to achieve when working on a suitable grid (Just choose something that fits your dimensions and then stick with it.
KiCad also has: PCB Editor / Tools / Cleanup Graphics / Fix discontinuities in board outlines This does work, but it may fix issues in less desirable ways then fixing it manually.