A method of printing a three-dimensional structure with a printing system, comprising: receiving reservoir identification information corresponding to a reservoir of a printing device filled with a structural print material; receiving multiple separate image files including a greyscale image file and at least one color file (802, 806); wherein the greyscale image file includes a shade level for each pixel of a greyscale image, wherein the shade levels in the greyscale image file take on values in a range between white and black, including a plurality of grey shade levels between white and black; selecting one image file of the separate image files; determining if the selected image file is for 3D printing; if the selected image file is for 3D printing, instructing the printing device to print the image file using the reservoir corresponding to the reservoir identification information; wherein the three-dimensional structure is formed as the printing device prints the image file; wherein each location on an upper surface of the three-dimensional structure has a corresponding pixel in the greyscale image; wherein a height of the three-dimensional structure at each location is determined by the shade level for the corresponding pixel; wherein the printing device dispenses more structural print material at a first location corresponding with a first pixel in the greyscale image having a first shade level than at a second location corresponding with a second pixel in the greyscale image having a second shade level that is lighter than the first shade level; wherein the method further includes receiving a predetermined maximum height for the three-dimensional structure; wherein locations of the upper surface of the three-dimensional structure having the predetermined maximum height correspond to pixels in the greyscale image with black shade levels; and wherein a relationship between the height of the three-dimensional structure at each location and the shade level of each pixel in the greyscale image corresponding to each location is a linear relationship. receiving reservoir identification information corresponding to a reservoir of a printing device filled with a structural print material; receiving multiple separate image files including a greyscale image file and at least one color file (802, 806); wherein the greyscale image file includes a shade level for each pixel of a greyscale image, wherein the shade levels in the greyscale image file take on values in a range between white and black, including a plurality of grey shade levels between white and black; selecting one image file of the separate image files; determining if the selected image file is for 3D printing; if the selected image file is for 3D printing, instructing the printing device to print the image file using the reservoir corresponding to the reservoir identification information; wherein the three-dimensional structure is formed as the printing device prints the image file; wherein each location on an upper surface of the three-dimensional structure has a corresponding pixel in the greyscale image; wherein a height of the three-dimensional structure at each location is determined by the shade level for the corresponding pixel; wherein the printing device dispenses more structural print material at a first location corresponding with a first pixel in the greyscale image having a first shade level than at a second location corresponding with a second pixel in the greyscale image having a second shade level that is lighter than the first shade level; wherein the method further includes receiving a predetermined maximum height for the three-dimensional structure; wherein locations of the upper surface of the three-dimensional structure having the predetermined maximum height correspond to pixels in the greyscale image with black shade levels; and wherein a relationship between the height of the three-dimensional structure at each location and the shade level of each pixel in the greyscale image corresponding to each location is a linear relationship.