A 3D printing system, comprising a heated chamber; a printing base plate mounted inside the heated chamber; a cooling unit mounted outside and above the heated chamber; a printing nozzle; wherein the cooling unit is configured to surround the printing nozzle's upper side outside the heated chamber for cooling the printing nozzle's upper side and wherein the printing nozzle's lower side is mounted inside the heated chamber; and a nozzle heating unit mounted inside the heated chamber and around the printing nozzle's lower side at a distance from the outer surface of the printing nozzle; the heating unit configured to heat the printing nozzle's lower side; the system configured to receive a printing material for printing a 3D model inside the heated chamber.