Exploiting nanostructured materials' characteristics and properties in stereolithography (SL) may open new markets for unique rapidly manufactured functional devices. Controlled amounts of multi-walled carbon nanotubes (MWCNTs) were successfully dispersed in SL epoxy-based resins and complex three-dimensional (3D) parts were successfully fabricated by means of a modified SL setup. The effect of the nanosized filler was evaluated by means of mechanical testing. Small concentrations of MWCNTs resulted in significant effects on the physical properties of the polymerized resin. A MWCNT concentration of 0.05% (w/v) increased the ultimate tensile stress and fracture stress an average of 17% and 37%, respectively. Increasing the MWCNT concentration to 0.5% (w/v) enhanced the integrity of the nanocomposite samples over much wider operating temperatures. Sample parts were characterized by scanning and transmission electron microscopy to measure the impact of this particular nanomaterial on the morphology of the nanocomposite samples and results showed affinity between the constituents and identified buckled nanotubes that illustrated strong interfacial bonding. These improved physical properties may provide opportunities for using nanocomposite SL resins in end-use applications. Varying types and concentrations of nanomaterials can be used to tailor existing SL resins for particular applications.