The point about designing in CAD is very relevant - I spent the final 20 years of my working life designing mechanical components & machinery ;layouts. I used high end software, CADAM, CATIA, IDEAS , Inventor - which took a long time to learn ( not to mention expensive training courses ). It's all very well making a 3D CAD model, but making an accurate model depends not only on your own skill, but the accuracy of the information you have - just as an example, how would you model the nose of an F-16? It's not a simple ogive, it's flattened, top to bottom, subtly blended - not something you'd knock out in an hour or so!
I used to deal with a rapid-prototyping company, and I visited their site quite regularly, and their equipment was awesome, Stereo lithography ( SLA ) & laser sintering (SLS ), as well as the resin bath - all of which was very expensive & needed highly trained engineers to get the best out of them ( They ran a 3-shift system for maximum return on their investment ). The largest 3D printed component I had made was a 4-cylinder diesel engine cylinder head ( of my design ), in transparent resin, so we could tweak the flow of water coolant through the head, it took about a week to print, and a day or so to cure! No idea of the cost, but suggestions of further prints were vetoed!
Dave