An example of an apparatus is provided. The apparatus includes an input device to receive design data. The design data includes information about a geometry and load characteristics of an object. The apparatus further includes a structural design engine to generate print data to print the object on a three-dimensional printer based on the design data. The apparatus also includes a fluid design engine to generate fluidic data. The fluidic data represents a fluid channel within the object. In addition, the apparatus includes an output engine to generate an output file based on the print data and the fluidic data.