An apparatus for generating data representations of an object for additive manufacturing, the apparatus comprising: at least one processor to determine two-dimensional slices (311a, 311b, 501, 504) for each of a plurality of 3D models of objects, wherein the 2D slices (311a, 311b, 501, 504) are for coordinates along a slicing axis; and characterized in that: for each 2D slice (311a, 311b, 501, 504) of each 3D model, the processor is to: determine whether the 2D slice (311a, 311b, 501, 504) is complete or incomplete for additive manufacturing, wherein a 2D slice (311a, 311b, 501, 504) is determined to be complete when the boundary forms a closed polygon and is determined to be incomplete when it is determined that the boundary has a gap; in response to determining the 2D slices (311a, 311b, 501, 504) are complete, combine corresponding 2D slices (311a, 311b, 501, 504) of the plurality of 3D models for each coordinate according to a Boolean operation to generate combined 2D slices printable by an additive manufacturing system, wherein the Boolean operation comprises at least one of AND, OR, and XOR; and. in response to the at least one processor determining that at least one of the 2D slices (311a, 311b, 501, 504) is incomplete, generating an indication of a defective 3D model. at least one processor to determine two-dimensional slices (311a, 311b, 501, 504) for each of a plurality of 3D models of objects, wherein the 2D slices (311a, 311b, 501, 504) are for coordinates along a slicing axis; and characterized in that: for each 2D slice (311a, 311b, 501, 504) of each 3D model, the processor is to: determine whether the 2D slice (311a, 311b, 501, 504) is complete or incomplete for additive manufacturing, wherein a 2D slice (311a, 311b, 501, 504) is determined to be complete when the boundary forms a closed polygon and is determined to be incomplete when it is determined that the boundary has a gap; in response to determining the 2D slices (311a, 311b, 501, 504) are complete, combine corresponding 2D slices (311a, 311b, 501, 504) of the plurality of 3D models for each coordinate according to a Boolean operation to generate combined 2D slices printable by an additive manufacturing system, wherein the Boolean operation comprises at least one of AND, OR, and XOR; and. in response to the at least one processor determining that at least one of the 2D slices (311a, 311b, 501, 504) is incomplete, generating an indication of a defective 3D model. determine two-dimensional slices (311a, 311b, 501, 504) for each of a plurality of 3D models of objects, wherein the 2D slices (311a, 311b, 501, 504) are for coordinates along a slicing axis; and characterized in that: for each 2D slice (311a, 311b, 501, 504) of each 3D model, the processor is to: determine whether the 2D slice (311a, 311b, 501, 504) is complete or incomplete for additive manufacturing, wherein a 2D slice (311a, 311b, 501, 504) is determined to be complete when the boundary forms a closed polygon and is determined to be incomplete when it is determined that the boundary has a gap; in response to determining the 2D slices (311a, 311b, 501, 504) are complete, combine corresponding 2D slices (311a, 311b, 501, 504) of the plurality of 3D models for each coordinate according to a Boolean operation to generate combined 2D slices printable by an additive manufacturing system, wherein the Boolean operation comprises at least one of AND, OR, and XOR; and. in response to the at least one processor determining that at least one of the 2D slices (311a, 311b, 501, 504) is incomplete, generating an indication of a defective 3D model. determine whether the 2D slice (311a, 311b, 501, 504) is complete or incomplete for additive manufacturing, wherein a 2D slice (311a, 311b, 501, 504) is determined to be complete when the boundary forms a closed polygon and is determined to be incomplete when it is determined that the boundary has a gap; in response to determining the 2D slices (311a, 311b, 501, 504) are complete, combine corresponding 2D slices (311a, 311b, 501, 504) of the plurality of 3D models for each coordinate according to a Boolean operation to generate combined 2D slices printable by an additive manufacturing system, wherein the Boolean operation comprises at least one of AND, OR, and XOR; and. in response to the at least one processor determining that at least one of the 2D slices (311a, 311b, 501, 504) is incomplete, generating an indication of a defective 3D model.