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. <EOS>