A tool for forming a dental restoration includes a mold body configured to combine with a tooth of a patient to define a mold cavity encompassing at least a portion of desired tooth structure of the tooth. In some examples, the portion of desired tooth structure defines an interproximal surface of the tooth. The mold body may include, in some examples, a base member configured to provide a customized fit with at least one tooth of the patient to attach the mold body to the at least one tooth, and an interproximal member extending from the base member and configured to be disposed between adjacent teeth of the patient when the base member is fit over the at least one tooth. The interproximal member defines a surface of the mold cavity.