Abstract: A method of creating instructions for an FFF printer for printing an infill structure of a 3D object is described. Instructions are created for printing a first layer (1) comprising a number of substantially parallel traces (11) that are separated by intermediate elongated first voids (12) with a first predefined width, and for printing a second layer (2) with traces (21) running substantially in parallel to the traces of the first layer, but with a first offset to the traces of the first layer, such that the traces of the second layer are arranged above the elongated first voids in the first layer, and for printing a third layer (3) with traces (31) running substantially in parallel to the traces of the second layer, but with a second offset to the traces of the second layer, wherein the traces in the third layer are separated by intermediate elongated third voids.