A method of additive manufacturing of a three-dimensional object, comprises: dispensing from a first array of nozzles a modeling material formulation containing a polyimide precursor to form a layer in a configured pattern corresponding to a shape of a slice of the object; applying to the layer ultraviolet radiation and infrared radiation from two different radiation sources; and repeating the dispensing and the application of radiation to form a plurality of layers in configured patterns corresponding to shapes of other slices of the object. Optionally, an additional modeling material formulation or a support material formulation is dispensed from a second array of nozzles.