Printed circuit board (PCB) assemblies must fit into unusual spaces for many real-life, high temperature applications such as sensors and actuators. This paper details the design and manufacture of a complex control circuit for a jet engine fuel flow valve. “Origami” was needed to fit this control circuitry into the tight space in the valve, this was achieved using a high temperature flex rigid PCB assembly. The valve was mounted on a hot section of the engine, and the assembly was tested for its capability to operate at 178°C and withstand multiple thermal cycles of −55°C and 175°C during its operational life. Various component joining media were investigated to extend the life of the assembly. The project also developed a one-time programmable (OTP) memory aimed at up to 300°C operation for on board memory to provide calibration data or boot memory for high temperature microcontrollers or processors. The device was based on Micro-Electro-Mechanical Systems (MEMS) technology.