This paper shows an engineering design process (EDP) of a lateral flexible, non-cylindrical drive shaft as a critical part for a jet engine, which will lead to an optimised design, considering the restrictions of the manufacturing processes. The relevant parameters of the EDP like layup, material, shaft-shape, winding angle and thickness are analysed regarding their influence on each other and on the component properties. Methods for the determination of optimal parameters are described. With the help of analytical models for shaft dimensioning and manufacturing analysis the parameters for a preliminary design are defined. For a validation of the manufacturing analysis, scaled specimen are subjected to winding tests using additively manufactured cores. A numerical model of the shaft, also enabling a stiffness analysis, verifies the analytical shaft dimensioning. Within the manufacturing evaluation trials, an optical measurement of the resulting fibre angles is carried out. This enables an exact verification of the fibre angles as well as a feedback into the numerical model. With the help of this digital twin, any fibre angle deviations occurring during production can be directly taken into account in the strength and stiffness analysis.