A method of forming an orthodontic appliance, comprising both an elastic material and a reinforcing material, wherein the orthodontic appliance comprises tooth sockets that correspond to each tooth on the dental arch, the elastic material being in an amount that imparts to the appliance elastic properties such that the appliance exerts a continuous aligning force on a tooth or teeth along a dental arch; wherein the elastic material accounts for all or substantially all the elastic properties of the appliance; wherein the reinforcing material being polyester fibers or polyethylene fibers; wherein the elastic material comprises at least 10 wt% of the appliance forming materials; wherein the elastic material is other than polyester; wherein the elastic material has an elasticity such that it is capable of being stretched at least 300% of its original length; comprising: creating a dental model of a patient tooth and bite, constructing individual teeth from the dental model, moving a tooth or teeth of target of alignment according to a prescription by a treating doctor to create an aligned dental model of the patient, forming at least one appliance from the aligned dental model of the patient; forming the appliance by casting comprising: 3D printing a cast-able appliance using a cast-able material, fabricating a mold from the cast-able appliance, and injecting into the mold the appliance forming material to form the appliance. wherein the orthodontic appliance comprises tooth sockets that correspond to each tooth on the dental arch, the elastic material being in an amount that imparts to the appliance elastic properties such that the appliance exerts a continuous aligning force on a tooth or teeth along a dental arch; wherein the elastic material accounts for all or substantially all the elastic properties of the appliance; wherein the reinforcing material being polyester fibers or polyethylene fibers; wherein the elastic material comprises at least 10 wt% of the appliance forming materials; wherein the elastic material is other than polyester; wherein the elastic material has an elasticity such that it is capable of being stretched at least 300% of its original length; comprising: creating a dental model of a patient tooth and bite, constructing individual teeth from the dental model, moving a tooth or teeth of target of alignment according to a prescription by a treating doctor to create an aligned dental model of the patient, forming at least one appliance from the aligned dental model of the patient; forming the appliance by casting comprising: 3D printing a cast-able appliance using a cast-able material, fabricating a mold from the cast-able appliance, and injecting into the mold the appliance forming material to form the appliance. creating a dental model of a patient tooth and bite, constructing individual teeth from the dental model, moving a tooth or teeth of target of alignment according to a prescription by a treating doctor to create an aligned dental model of the patient, forming at least one appliance from the aligned dental model of the patient; forming the appliance by casting comprising: 3D printing a cast-able appliance using a cast-able material, fabricating a mold from the cast-able appliance, and injecting into the mold the appliance forming material to form the appliance. 3D printing a cast-able appliance using a cast-able material, fabricating a mold from the cast-able appliance, and injecting into the mold the appliance forming material to form the appliance.