Provided is an additive manufacturing process that uses an upward-pointing illumination source, such as a laser, projected through a substrate so as to solidify particulate matter supported by the substrate. The process is then repeated to build a hanging part layer by layer, for example by replenishing particulate matter on the substrate, or by moving the part a second substrate that supports other particulate matter. The disclosed process eliminates the need for a large powder bed and also allows for sintering of different powders in a single layer so as to give rise to parts that include layers that are themselves made from multiple materials. Also provided are related methods, include methods of incorporated cured resins into parts made by fusing particulate matter.