Knowledge of software tools specific to your area of interest, such as CAD (NX, Solidworks, Fusion360, or similar), orbit simulation (STK, Orekit), embedded Linux development (Yocto/OpenEmbedded), PCB design (Altium, KiCad, or similar) etc. Knowledge of hardware tools specific to your area of interest, such as electrical test equipment (power supplies, oscilloscopes), manufacturing equipment (3D printers, mills, lathes), RF test equipment (signal generators, spectrum analyzers) etc.