The task of this paper is to design, develop and evaluate modular 3D printer with a large print area and the possibility to transition from Cartesian coordinate system to the polar coordinate system. 3D printers offer reduced manufacturing costs, rapid prototyping, greater design freedom and reduces the cost of manufacturing. 3D printers are used in almost all branches of industry ranging from aeronautics to biomedicine. This technology offers great opportunities for small and middle sized companies and gives a whole new meaning for large companies that have to adapt to this new way of production. 3D printer in this thesis is designed in CAD tool and then laser cut. It’s made from acrylic plastic due to lower cost of production and greater ability to mold and good thermal and structural characteristics. FDM/FFD printing technology was chosen beacause it offers great ability to print a large variety of materials such as polymers, wood or even bronze and carbon materials such as carbon fiber. PLA and ABS are used as a filament for making models because of low price and good quality of models. Arduino development system was used. This thesis used an Arduino Mega 2560 microcontroller, Nema 17 and GT2 stepping motors connected to the RAMPS board where they were controlled with A4988 drivers. RAMPS regulates the voltage characteristic of 3D printer, thermistors and measures the temperature of the print bed and the printhead. It’s shown how to connect and operate certain parts od 3D printer. The design of the model is made in CAD software. CAM software is used to generate G-code that determines where the axis move and slicer for structural modeling.