Abstract: Switching devices for a printing mode of a 3D printer are disclosed. In some embodiments, the switching devices includes: a component platform with at least two platform bodies (200); at least two handpiece guiding parts (110); at least two handpiece guiding parts (110); at least two platform guiding parts (210); at least two handpiece transmission mechanisms (120); a handpiece drive mechanism configured to drive the handpiece transmission mechanisms (120) to move synchronously; at least two platform transmission mechanisms (220); and a platform drive mechanism configured to drive the platform transmission mechanisms (220) to move synchronously.

Abstract: A throat structure for a 3D printer according to an embodiment includes a cold zone for heat dissipation, a hot zone for heating, and a thermal insulation zone. The cold zone for heat dissipation has a titanium throat outer tube body and a teflon throat inner tube body, and the teflon throat inner tube body is socketed in the titanium throat outer tube body. The hot zone for heating has a heating block connection zone and a nozzle connection zone. The heating block connection zone is located on an external side of the hot zone for heating, and the nozzle connection zone is located at a lower part of the hot zone for heating. The thermal insulation zone is connected to the titanium throat outer tube body such that an area of the hot zone for heating is reduced and a printing material extrusion amount is controlled.