Purpose　In　some　three-dimensional　(3D)　printing　application　scenarios,　e.g.,　model　manufacture,　it　is　necessary　to　print　large-sized　objects.　However,　it　is　impossible　to　implement　large-size　3D　printing　using　a　single　projector　in　digital　light　processing　(DLP)-based　mask　projection　3D　printing　because　of　the　limitations　of　the　digital　micromirror　device　chips.　Design/methodology/approach　A　multi-projector　DLP　with　energy　homogenization　(EHMP-DLP)　scheme　is　proposed　for　large-size　3D　printing.　First,　a　large-area　printing　plane　is　established　by　tiling　multiple　projectors.　Second,　the　projector　set＇s　tiling　pattern　is　obtained　automatically,　and　the　maximum　printable　plane　is　determined.　Third,　the　energy　is　homogenized　across　the　entire　printable　plane　by　adjusting　gray　levels　of　the　images　input　into　the　projectors.　Finally,　slices　are　automatically　segmented　based　on　the　tiling　pattern　of　the　projector　set,　and　the　gray　levels　of　these　slices　are　reassigned　based　on　the　images　of　the　corresponding　projectors.　Findings　Large-area　high-intensity　projection　for　mask　projection　3D　printing　can　be　performed　by　tiling　multiple　DLP　projectors.　The　tiled　projector　output　energies　can　be　homogenized　by　adjusting　the　images　of　the　projectors.　Uniform　ultraviolet　energy　is　important　for　high-quality　printing.　Practical　implications　A　prototype　device　is　constructed　using　two　projectors.　The　printable　area　becomes　140　x　210　mm　from　the　original　140　x　110　mm.　Originality/value　The　proposed　EHMP-DLP　scheme　enables　3D　printing　of　large-size　objects　with　linearly　increasing　printing　times　and　high　printing　precision.　A　device　was　established　using　two　projectors　to　practice　the　scheme　and　can　easily　be　extended　to　larger　sizes　by　using　more　projectors.