Additive technologies, also known as 3D printing technologies, are becoming more and more widely used in industrial conditions for the production of finished elements, especially for the production of parts that would be very difficult or even impossible to produce using existing technologies. Technologically difficult elements include parts with a thin-walled spatial structure. This work presents the research results and describes the problems of producing specimens of thin-walled profiles filled with an appropriate spatial structure, also thin-walled, using 3D printing technology. The results of a three-point bending test of specimens of various lengths and specimens filled with chemically cured resin are presented. Print simulations were discussed, paying attention to problems related to applying lines and layers in FDM/FFF technology and the impact of print technological parameters on the properties of the manufactured specimens.