Systems and methods fabricate composite preforms in a flat or unfolded format. Following fabrication, the preform is folded and placed in or around a mold for curing. To facilitate folding and produce strong parts, the preform is fabricated with integrated, 3D woven joints at preform edges. These joints connect the folded preform portions to other parts of the preform, such as other unfolded or folded preform portions or internal features. Integrated joints may be flexible to facilitate assembly prior to curing. The unfolded preform design may be generated from a preform model by splitting the preform model at an initial joint location, unfolding the preform model into an unfolded preform, creating joint connectors in the unfolded preform at the initial joint location, determining a fiber layup of the unfolded preform, and generating fabrication data.