This document discusses a review of literature on research related to software and tool path generation for fused deposition modeling (FDM) 3D printing. It outlines three main categories of FDM research: novel applications, materials, and system improvements. Much of the research on system improvements focuses on software/tool path generation, layer algorithms, and part orientation optimization. The review then discusses some specific patented techniques for FDM like adaptive filament deposition and planar layer deposition. It also notes that current research on variable nozzle shapes/diameters aims to reduce errors from using a constant circular nozzle profile.