Learn the following skills, or hire people who have them. Details depend on what you're building. - Electronics - PCB design, with software like Altium or

Learn the following skills, or hire people who have them. Details depend on what you're building. - Electronics - PCB design, with software like Altium or KiCad - CAD software like Solidworks or Fusion - Program emebedded firmware in a low level language like C or Rust - Learn how to read datasheets, and interact with hardware at the register level - How to select parts and manage BOM - How to choose manufacturing techniques, like injection molding, extrusion, milling etc - Regulatory compliance. Eg, are there safety concerns? Does it contain lead? Does it radiate? Short answer is, you need to figure out what your project requirement are, and learn the relevant skills.