Soybean oil/epoxy-based composites are prepared by solid freeform fabrication (SFF) methods. SFF methods built materials by the repetitive addition of thin layers. The mixture of epoxidized soybean oil and epoxy resin is modified with di-, tri-, or polyethylene amine gelling agent to solidify the materials until curing occurs. The high strength and stiffness composites are formed through fiber reinforcement. E-glass, carbon, and mineral fibers are used in the formulations. The type of fiber affects the properties of the composites. It was found that a combination of two types of fibers could be used to achieve higher strength and stiffness parts than can be obtained from a single fiber type. In addition, the effects of curing temperature, curing time, and fiber concentration on mechanical properties of composites are studied and reported. (C) 2004 Wiley Periodicals, Inc.