In　3D　printing,　it　is　critical　to　use　as　few　as　possible　supporting　materials　for　efficiency　and　material　saving.　Multiple　model　decomposition　methods　and　multi-DOF　(degrees　of　freedom)　3D　printers　have　been　developed　to　address　this　issue.　However,　most　systems　utilize　model　decomposition　and　multi-DOF　independently.　Only　a　few　existing　approaches　combine　the　two,　i.e.　partitioning　the　models　for　multi-DOF　printing.　In　this　paper,　we　present　a　novel　model　decomposition　method　for　multi-directional　3D　printing,　allowing　consistent　printing　with　the　least　cost　of　supporting　materials.　Our　method　is　based　on　a　global　optimization　that　minimizes　the　surface　area　to　be　supported　for　a　3D　model.　The　printing　sequence　is　determined　inherently　by　minimizing　a　single　global　objective　function.　Experiments　on　various　complex　3D　models　using　a　five-DOF　3D　printer　have　demonstrated　the　effectiveness　of　our　approach.