Provided are methods for producing magnetic composites. In some embodiments, the methods include providing a material in a non-continuous solid form; providing optically resonant particles dispersed within at least a region of said material; and exposing the optically resonant particles to electromagnetic radiation to be absorbed thereby to optically resonate to generate heat to fuse together portions of the material in thermal contact therewith. In some embodiments, the optically resonant particles have magnetic properties and/or are adapted to have magnetic properties induced by a stimulus, and the material is a non-magnetic material. Also provided are systems, computer program products, and packages adapted to implement the presently disclosed methods.