Sorry for the multiple posts. If you have a technical college that teaches machining and CNC (computer numerical control) machining, it would be worthwhile to take the courses prior to buying machines. It’s a cheap way to learn and use the equipment before you make the investment. I had 1 course for general machining using mills and lathes. I had a subsequent course for CNC machining and programming (CAM - computer aided machining). I had a separate class for CAD (computer aided design). Over the years, I have learned AutoCAD, Pro/E, CATIA V5, MasterCam, SmartCAM and Pro/Manufacture. Currently, I’m learning Siemens NX for work. MasterCam was probably the best CAM software for the average person and business from my list. Pro/Manufacture was the most customizable but it was way too expensive and slower to program with. Pro/E, Catia, NX are all really expensive and geared towards large companies with large, complex products.
For metallics and plastics, many home and small to medium businesses use Solidworks for CAD design. It has powerful capabilities for design and working with 3D scanning devices and software if you want to get into reverse engineering. Then use MasterCAM to program the CNC machines.
I have been considering starting my own business. Right now, I would be more inclined to skip purchasing the production equipment and contract it out. That way, you aren’t limited to certain systems. Metallic printing is getting really advanced to the point you can commission businesses to print gears suitable for vehicle camshaft gears, aluminum intake manifolds and inconel exhaust manifolds. Couple that with 3D scanning, you can disassemble engine parts, scan them into CAD and then modify the parts. Depending on tolerance requirements, you may need to measure specific features with a caliper or micrometer but you can generally design and fabricate OEM fitting parts.