Abstract Fused filament fabrication (FFF) is a method used to fabricate initial prototypes out of polymeric materials, with printed parts often being used as load‐carrying elements. The mechanical properties of various polymer materials produced under certain printing conditions exhibit superior strength and ductility and may serve as an inexpensive replacement for metal or wooden parts. To gain knowledge of 3D‐printed part strength and compare the quality of filament material from several manufacturers, this study characterizes the mechanical properties of parts printed from various commercial FFF feedstocks. Uniaxial tensile testing is performed to determine the ultimate tensile strength, Young's modulus, and fracture strain of polymer and composite materials. This study, thus, demonstrates the importance and necessity of evaluating the filament feedstock prior to printing, as polymeric filaments of the same type of polymer can have different mechanical properties.