We describe a project-based physics lab, which we proposed to third-year university students. Theses labs are based on new open-source low-cost equipment (Arduino microcontrollers and compatible sensors) which allows a complete autonomy for the students. The students develop their own experimental setup and study the physics topic of their choice. Based on the results obtained by the students and on various surveys, we discuss how these projects let the students discover the reality of experimental physics and how engaging these new tools are. Technical specifications of the acquisition material and case studies are also presented for practical implementation in other universities.