What is FDM? Fused Deposition Modeling (FDM) is a type of additive manufacturing process used for creating tangible 3-dimensional objects from CAD-designed digital files. Invented by S. Scott Crump in 1989, this trademarked 3D printing method uses thin strands of heated thermoplastic filament to build objects. A coil of thermoplastic filament is fed into an extrusion nozzle that heats the filament into a semi-liquid state where it is then deposited in small beads along a preset path. Once one layer is finished, the process is repeated, layer-by-layer, until the object is completed. Extremely similar methods have been created since FDM’s inception but the term itself is trademarked by the Crump co-founded company Stratasys, LTD.