An apparatus for creating multiple zones of parameters for a three-dimensional object formed by additive manufacturing, the apparatus comprising a processor and a memory storing executable instructions that in response to execution by the processor cause the apparatus to at least: receive solid model of the three-dimensional object ; generate a shell of the three-dimensional object based on the solid model ; divide the shell into zones and thereby form zones of the three-dimensional object ; define or select a set of parameters for the additive manufacturing system to form each of the zones of the three-dimensional object , the set of parameters being different between the zones; form layer data defining a plurality of layers of the shell for use in forming the zones and thereby the three-dimensional object ; create a tool path from the layer data, and including the apparatus being caused to merge the layer data for the zones, for receipt by an additive manufacturing system configured to manipulate build material to form the three-dimensional object on a layer-by-layer basis, the additive manufacturing system includes a laser configured to emit a beam onto build material to form the three-dimensional object on a layer-by-layer basis, and the set of parameters include values for one or more of beam power, beam offset, laser speed, laser time delay, laser acceleration parameters, laser focus, layer thickness, hatching pattern, number of boundary or contour profiles; wherein the shell of the three-dimensional object is in a coordinate system with orthogonal axes including x- and y-axes, and a z-axis, and wherein the apparatus being caused to create the tool path includes being caused to one or more of (a) add continuity in the tool path for any beam offset that differs in the set of parameters between the zones, (b) include a finger joint in the tool path in the direction of the z-axis where the zones of the three-dimensional object are joined, (c) reorient the tool path layer-per-layer in the directions of the x- and/or y-axes, or (d) offset a contour endpoint of the tool path for each zone. receive solid model of the three-dimensional object ; generate a shell of the three-dimensional object based on the solid model ; divide the shell into zones and thereby form zones of the three-dimensional object ; define or select a set of parameters for the additive manufacturing system to form each of the zones of the three-dimensional object , the set of parameters being different between the zones; form layer data defining a plurality of layers of the shell for use in forming the zones and thereby the three-dimensional object ; create a tool path from the layer data, and including the apparatus being caused to merge the layer data for the zones, for receipt by an additive manufacturing system configured to manipulate build material to form the three-dimensional object on a layer-by-layer basis, the additive manufacturing system includes a laser configured to emit a beam onto build material to form the three-dimensional object on a layer-by-layer basis, and the set of parameters include values for one or more of beam power, beam offset, laser speed, laser time delay, laser acceleration parameters, laser focus, layer thickness, hatching pattern, number of boundary or contour profiles; wherein the shell of the three-dimensional object is in a coordinate system with orthogonal axes including x- and y-axes, and a z-axis, and wherein the apparatus being caused to create the tool path includes being caused to one or more of (a) add continuity in the tool path for any beam offset that differs in the set of parameters between the zones, (b) include a finger joint in the tool path in the direction of the z-axis where the zones of the three-dimensional object are joined, (c) reorient the tool path layer-per-layer in the directions of the x- and/or y-axes, or (d) offset a contour endpoint of the tool path for each zone. <EOS>