To offer extruded Wood-Plastic Composite (WPC) cladding more design options, they could be thermally reshaped in an industrial post-process. However, there is little knowledge about how temperature, heating time, bending radius and fibre content impact mechanical properties and memory behaviour after thermoforming. Therefore, two compound formulations with different wood contents were investigated. While higher heat facilitates forming with smaller radii, strength significantly decreases, especially for thicker samples. In contrast, stiffness is less affected. Retention forces increase with narrow curving, but lower fibre contents counteract this. In contrast to heating duration, temperature tends to produce compound-independent reactions during conditioning, and among geometric parameters, the shaping radius exerts universal responses, more than the material thickness. The fibre content, as a compound-specific factor, affects the material behaviour entirely. For implementation on industrial scale, rupture modulus and retention force should be used for development and process control, whereas research should aim at compound optimisation.