This paper presents an original multi-sensor system for 3D orientation determination based on only 4 MEMS sensors. MEMS sensors are manufactured on a cheap standard technology from NXP Semiconductors using TMAH front side wet etching with no additional masking step. This very low cost manufacturing process makes the system suitable for various consumer applications. Electronic architecture for signal conditioning is detailed covering issues regarding the design of piezoresistor based systems (offsets, flicker noise...). Finally, the complete system has been prototyped proving the interest and the feasibility of such devices.