A method of automatically forming and feeding a multicomponent feedstock being extruded by a print head of a 3D printer , the method comprising, under processor control concurrent with and in cooperation with control of a printer tool path: at a multicomponent feedstock source coupled to but spaced from the print head by a feedstock feed path: automatically positioning a portion of a first feedstock along the feed path, wherein positioning the portion of the first feedstock includes feeding a distal end of the first feedstock along the feed path toward the print head, and cutting the first feedstock at a pre-determined length to provide a length of the first feedstock having a proximal end and the distal end; automatically positioning a portion of a second feedstock along the feed path and in line with the portion of the first feedstock , the portions of feedstock being aligned in series to form the multicomponent feedstock ; and feeding the multicomponent feedstock along the feed path to the print head, and tracking an amount of the multicomponent feedstock as it is fed into the print head with a feedstock monitoring device mounted adjacent to a feedstock pathway into the print head; wherein the cooperation comprises adjusting a production rate of the multicomponent feedstock in response to the amount of the multicomponent feedstock fed into the print head; and wherein the first feedstock and the second feedstock are spooled feedstock in the form of filament. at a multicomponent feedstock source coupled to but spaced from the print head by a feedstock feed path: automatically positioning a portion of a first feedstock along the feed path, wherein positioning the portion of the first feedstock includes feeding a distal end of the first feedstock along the feed path toward the print head, and cutting the first feedstock at a pre-determined length to provide a length of the first feedstock having a proximal end and the distal end; automatically positioning a portion of a second feedstock along the feed path and in line with the portion of the first feedstock , the portions of feedstock being aligned in series to form the multicomponent feedstock ; and feeding the multicomponent feedstock along the feed path to the print head, and automatically positioning a portion of a first feedstock along the feed path, wherein positioning the portion of the first feedstock includes feeding a distal end of the first feedstock along the feed path toward the print head, and cutting the first feedstock at a pre-determined length to provide a length of the first feedstock having a proximal end and the distal end; automatically positioning a portion of a second feedstock along the feed path and in line with the portion of the first feedstock , the portions of feedstock being aligned in series to form the multicomponent feedstock ; and feeding the multicomponent feedstock along the feed path to the print head, and tracking an amount of the multicomponent feedstock as it is fed into the print head with a feedstock monitoring device mounted adjacent to a feedstock pathway into the print head; wherein the cooperation comprises adjusting a production rate of the multicomponent feedstock in response to the amount of the multicomponent feedstock fed into the print head; and wherein the first feedstock and the second feedstock are spooled feedstock in the form of filament. <EOS>