Osteomas are benign, well-differentiated bony tumors characterized by gradual progression, commonly observed within the craniofacial skeleton. This case report aims at describing the successful surgical treatment of giant frontal osteomas thanks to additive manufacturing technologies. The osteomas were located on the external table of the parietal and frontal bones with complete invasion of the anterior wall of the right frontal sinus. Resection was performed with the help of three 3D printed surgical cutting guides to prevent damaging the inter-sinus septum, the right orbital roof and the posterior wall of the frontal sinus. Anterior frontal sinus wall was reconstructed with a 3D printed hydroxyapatite patient-specific implant called MyBone Custom Implant (MBCI). The 3D planning and accuracy of the additive manufacturing tools enabled to obtain good bone contacts . Ossification of the edges of the MBCI is visible on the six-month postoperative scans. The outcome of this reconstruction proved highly satisfactory both in terms of aesthetic results as well as restoring the bone integrity.