Abstract: Disclosed are composite filaments for 3D printing. The filaments typically have high strength, an appropriate resorption rate, and high biocompatibility. The filaments generally contain a matrix formed of a blend containing a bioresorbable polymer and an inorganic component. The filaments can be used to produce customized scaffolds for repairing bone defects following implantation in the site of the defect. The shape and size of the scaffold can be configured to fit in and conform to the bone defect. The scaffolds are especially useful in repairing critical sized bone defect, such as a critical sized bone defect in a weight-bearing long bone.