To　better　lay　out　3D　irregular　geometries　and　enhance　the　nesting　tightness　of　parts　in　non-stacked　additive　manufacturing,　a　spatial　nesting　strategy　is　proposed.　In　the　proposed　strategy,　based　on　the　idea　of　layering　and　slicing,　the　no-fit　polygon　of　space　(NFP-S)　system　composed　of　four　types　of　no-fit　polygon　(NFP)　is　established.　The　spatial　collision　detection　method　combining　the　NFP-S　and　the　orbital　sliding　approach　is　proposed.　In　the　same　layer　of　two　parts,　the　calculation　method　of　NFP　of　multiple　non-adjacent　polygons　is　proposed　to　realize　the　calculation　of　no-fit　polygon　of　layer　(NFP-L).　All　the　NFP-L　are　used　to　jointly　determine　the　NFP-S　of　the　part,　and　the　spatial　nesting　position　set　of　the　part　is　obtained.　Based　on　the　optimal　foraging　algorithm,　the　proposed　spatial　nesting　strategy　is　used　to　optimize　the　spatial　nesting　problem　in　additive　manufacturing.　The　feasibility　and　effectiveness　of　the　proposed　method　are　verified　by　experiments.　©　The　Author(s),　under　exclusive　licence　to　Springer　Nature　Switzerland　AG　2025.