A three-dimensional printing system for preparing a three-dimensional object made at least partially of an expanded polymer comprising: i) a printing device for preparing an expandable polymer melt and for depositing a strand of the expandable, expanding or expanded polymer onto a surface and ii) a three-dimensional movement device for adjusting the position of the printing device in a predefined three-dimensional matrix so as to allow to deposit the strand of expandable, expanding or expanded polymer at a predetermined time at a precise position within the three-dimensional matrix, wherein the printing device comprises: a) a feed section at the upstream end of the printing device, b) a heating section, c) a pressurizing section, d) a blowing agent supply line, e) a mixing section, f) a cooling section and g) a terminal printing head section at the downstream end of the printing device including a die for depositing the strand of expandable, expanding or expanded polymer onto the surface, wherein the mixing section and the cooling section are arranged downstream of the feed section, of the heating section and of the pressurizing section, wherein the blowing agent supply line has one or more discharge end(s), which is/are connected with one or more of the pressurizing section, the mixing section and the cooling section, characterized in that the cooling section f) is a tubular section, which comprises a tube, wherein a Peltier element, a resistance heater, a heat exchanger or cooling fins are provided on the outer wall of the tube, and wherein wherein the pressurizing section comprises a piston compressor, a screw compressor or a gear compressor. i) a printing device for preparing an expandable polymer melt and for depositing a strand of the expandable, expanding or expanded polymer onto a surface and ii) a three-dimensional movement device for adjusting the position of the printing device in a predefined three-dimensional matrix so as to allow to deposit the strand of expandable, expanding or expanded polymer at a predetermined time at a precise position within the three-dimensional matrix, wherein the printing device comprises: a) a feed section at the upstream end of the printing device, b) a heating section, c) a pressurizing section, d) a blowing agent supply line, e) a mixing section, f) a cooling section and g) a terminal printing head section at the downstream end of the printing device including a die for depositing the strand of expandable, expanding or expanded polymer onto the surface, a) a feed section at the upstream end of the printing device, b) a heating section, c) a pressurizing section, d) a blowing agent supply line, e) a mixing section, f) a cooling section and g) a terminal printing head section at the downstream end of the printing device including a die for depositing the strand of expandable, expanding or expanded polymer onto the surface, wherein the mixing section and the cooling section are arranged downstream of the feed section, of the heating section and of the pressurizing section, wherein the blowing agent supply line has one or more discharge end(s), which is/are connected with one or more of the pressurizing section, the mixing section and the cooling section, characterized in that the cooling section f) is a tubular section, which comprises a tube, wherein a Peltier element, a resistance heater, a heat exchanger or cooling fins are provided on the outer wall of the tube, and wherein wherein the pressurizing section comprises a piston compressor, a screw compressor or a gear compressor.