A directly fabricated intraoral appliance comprising: a 3D printed body composed of a plurality of additively manufactured layers forming a plurality of tooth-receiving cavities configured to receive a corresponding plurality of teeth of a patient's dentition, the 3D printed body comprising: a first one or more areas formed from a first polymeric material, the first one or more areas composed of a first cellular structure with a first network of interconnected unit cells, the first network of interconnected unit cells having a first elongation characteristic, the first elongation characteristic being characterized by a first elongation value, wherein the first elongation value corresponds to a first apparent Young's modulus selected from the range of 0.1 MPa to 1000 GPa, and wherein the first one or more areas form an interproximal region of at least two of the tooth-receiving cavities; and a second one or more areas, at least a portion of the second one or more areas being proximate to the first one or more areas, the second one or more areas formed from a second polymeric material having a second elongation characteristic, the second elongation characteristic being characterized by a second elongation value different from the first elongation value. a 3D printed body composed of a plurality of additively manufactured layers forming a plurality of tooth-receiving cavities configured to receive a corresponding plurality of teeth of a patient's dentition, the 3D printed body comprising: a first one or more areas formed from a first polymeric material, the first one or more areas composed of a first cellular structure with a first network of interconnected unit cells, the first network of interconnected unit cells having a first elongation characteristic, the first elongation characteristic being characterized by a first elongation value, wherein the first elongation value corresponds to a first apparent Young's modulus selected from the range of 0.1 MPa to 1000 GPa, and wherein the first one or more areas form an interproximal region of at least two of the tooth-receiving cavities; and a second one or more areas, at least a portion of the second one or more areas being proximate to the first one or more areas, the second one or more areas formed from a second polymeric material having a second elongation characteristic, the second elongation characteristic being a first one or more areas formed from a first polymeric material, the first one or more areas composed of a first cellular structure with a first network of interconnected unit cells, the first network of interconnected unit cells having a first elongation characteristic, the first elongation characteristic being characterized by a first elongation value, wherein the first elongation value corresponds to a first apparent Young's modulus selected from the range of 0.1 MPa to 1000 GPa, and wherein the first one or more areas form an interproximal region of at least two of the tooth-receiving cavities; and a second one or more areas, at least a portion of the second one or more areas being proximate to the first one or more areas, the second one or more areas formed from a second polymeric material having a second elongation characteristic, the second elongation characteristic being characterized by a second elongation value different from the first elongation value.