Polymer Design Guidelines
Material extrusion (a.k.a. fused deposition modelling or FDM) is an AM process in which material is selectively dispensed through a nozzle much like a hot-glue gun. Materials used are typically thermoplastic polymers and the part being constructed normally requires support structures for overhanging features. Some system use support material built from the same material as the print material, some use a different second material that is slightly easier to remove by mechanical force, and some use a second material that is soluble.