A patient-specific surgical guide (30) for intra-operatively producing a patient-specific augment is provided. A method using the same includes planning a patient-specific augment (22) using obtained patient imagery of a bone such as the scapula (24) adapted to receive a prosthesis such as a glenoid implant (26) to determine a size and shape of the patient-specific augment corresponding to the bone, creating a model of the patient-specific augment having the determined size and shape, and providing a patient-specific surgical guide, for example a semi-spherical shell-shaped milling guide (34) having cutting guide surfaces such as intersecting slots (46) which are customized in position and orientation and configured to guide a surgical implement such as a bone milling burr (52) to form the patient-specific augment corresponding to the 3D model. The patient-specific surgical guide is then used intra-operatively to create the augment corresponding to the 3D model.
