It is for these reasons that the fi

It is for these reasons that the field has focused on CaP-polymer composites, including those produced via room temperature or hot-melt extrusion–based 3D printing (32–34) or other forms of AM (35, 36). Nevertheless, these composites often still have suboptimal material, handling, and/or biological properties: Although composites with CaP, whether in hydrogel (37) or 3D-printed form (32–34), often have im- proved stiffness (elastic and compressive moduli) over pure polymers and increased mechanical elasticity or malleability over pure CaPs (5), the polymeric component often physically encapsulates the bioactive CaP particles, isolating them from the tissue and mitigating their therapeutic potential. In addition, many 3D-printed composites are fabricated with hot-melt fused deposition modeling or laser sintering techniques, which require temperatures greater than 100°C. This high-temperature pro- cessing precludes direct incorporation of biological molecules or factors (33) and is too slow for mass fabrication, with linear deposition rates not greater than 5 mm/s or volume deposition rates not greater than 1 mm3/s. Although these composites often do not undergo brittle fracture, their bioactivity is often limited, requiring surface modification with costly bio- molecules or other factors (38–40), which also complicate regulatory approval and translatability. Here, we report a new synthetic osteore- generative biomaterial, which we have called hyperelastic “bone” (HB), that avoids the technical, surgical, and manufacturing limitations of cur- rent bone graft materials.