This article describes the design and manufacture of an accessible and easy-to-use mechanical system as a teaching tool to learn the light diffraction phenomenon. The teaching tool was designed by modules and manufactured piece-piece in 3D printer technique. It was made in a polymer with a relatively low cost. This mechanical system facilitates that both teachers and students improve the teaching-learning processes. The didactic system is more reliable because it facilitates the verification of the diffraction theory in the Fraunhofer regime and in turn allows to study the decomposition of the white light of a fluorescent bulb in the different colors that compose it using diffraction gratings. This tool is supported with a mobile application of free and interactive access, in which teacher and students can check the results of the experiments. The diffraction patterns achieved through this mechanical system can eliminate the use of high-cost equipment that generally limits some of the experiments that take place in a physics course.