A 3D printing device for photopolymerization of a photosensitive synthetic resin by an exposure pattern, comprising - a synthetic resin bath for the photosensitive synthetic resin with a lifting device , wherein the photosensitive synthetic resin is polymerizable as a cured body on the lifting device by means of a light of a preset wavelength, and wherein the lifting device is formed to move the cured body upwards and out of the synthetic resin bath to change an exposure plane for the photosensitive synthetic resin with respect to the body; - a carrier medium , which is formed to transfer coupled-in light as a light guide by means of internal reflection, and comprising a coupling-in area and a coupling-out area , which are arranged in different sections of the carrier medium; - an illumination device , which is formed to radiate the light onto the coupling-in area ; wherein - the coupling-in area comprises a coupling-in deflection structure , which is adapted to couple light with the preset wavelength, which is incident from the illumination device on the coupling-in deflection structure , into the carrier medium towards the coupling-out area ; characterized in that - the coupling-out area is arranged below the synthetic resin bath and comprises a coupling-out deflection structure , which is formed and arranged to couple the coupled-in light with the preset wavelength, which is incident on the coupling-out deflection structure , as an exposure pattern out of the carrier medium onto the photosensitive synthetic resin of the synthetic resin bath for photopolymerization of the synthetic resin; - wherein the coupling-in deflection structure and the coupling-out deflection structure are formed as a holographic element with at least one optical grating, in particular a holographic volume grating or a holographic surface grating. - a synthetic resin bath for the photosensitive synthetic resin with a lifting device , wherein the photosensitive synthetic resin is polymerizable as a cured body on the lifting device by means of a light of a preset wavelength, and wherein the lifting device is formed to move the cured body upwards and out of the synthetic resin bath to change an exposure plane for the photosensitive synthetic resin with respect to the body; - a carrier medium , which is formed to transfer coupled-in light as a light guide by means of internal reflection, and comprising a coupling-in area and a coupling-out area , which are arranged in different sections of the carrier medium; - an illumination device , which is formed to radiate the light onto the coupling-in area ; wherein - the coupling-in area comprises a coupling-in deflection structure , which is adapted to couple light with the preset wavelength, which is incident from the illumination device on the coupling-in deflection structure , into the carrier medium towards the coupling-out area ; - the coupling-out area is arranged below the synthetic resin bath and comprises a coupling-out deflection structure , which is formed and arranged to couple the coupled-in light with the preset wavelength, which is incident on the coupling-out deflection structure , as an exposure pattern out of the carrier medium onto the photosensitive synthetic resin of the synthetic resin bath for photopolymerization of the synthetic resin; - wherein the coupling-in deflection structure and the coupling-out deflection structure are formed as a holographic element with at least one optical grating, in particular a holographic volume grating or a holographic surface grating. <EOS>