This research explores the production of fiberglass composite materials using an open mold process with pressing, aiming to overcome the uneven surfaces often produced by the hand lay-up method. Conducted in the Mechanical Engineering laboratories of Universitas Muhammadiyah Sidoarjo (UMSIDA) and Politeknik Negeri Malang, the study tested specimens using tensile testing (ASTM D638 Type I) and flexural testing (ASTM D790), along with surface flatness measurement via a dial indicator. The research varied the number of fiberglass layers (2, 3, and 4) and the pressing duration (3, 4, and 5 hours). Tensile tests showed the best stress and strain with 2 layers of fiberglass and 3 hours of pressing, with the "hours" factor contributing 55.28% to true stress and 45.23% to true strain. Flexural tests indicated the best stress and modulus of elasticity with 4 layers of fiberglass and 4 hours of pressing, with the "hours" factor contributing 31.48% to the modulus of elasticity. Optimal surface flatness was achieved with 3 layers of fiberglass and 4 hours of pressing, with the "hours" factor contributing 38.77%. Optimizing process parameters is essential for improving the quality of molded products and provides a foundation for developing a more efficient pressing method in future composite material production