Hi
If you intend to go into aerospace industry I can chime in on this since I’ve been working in it for bigger chunk of my life.
So what I can tell you about is its one of the toughest sectors. Profits, if any, are very slim. The best company I have ever worked for was a supplier which I do not want to name on public forums. Their profit was between 0.2-2% per month, while production and materials costs to have these products basically top notch was around 150-250 mil $$ per month, depending on customer orders and mostly which materials were used.
The processing itself requires highly trained personnel. You’ll need some serious engineers and various staff with a crapton of experience under their belt, and people like this (myself included) do not come cheap and are in high demand, meaning its not only expensive, but they have continuous job offers everywhere and if for whatever reasons they don’t like how they’re treated they will move on to the next one. Be prepared to shell out a starting base salary for low or no experience of around $75k/yr all the way up to around $300k/yr per employee, though most top out at around 120k, the ones higher then that will be your heads of projects and some will become management etc.
Next is the actual equipment and systems necessary to run such a business. Understand this is going to be very high cost, you can’t just use regular machinery and tooling like you would for parts going into automotive or home depot for example because the materials you will be working on are too often very high temperature, abrasion and corrosion resistant to various degrees, some very high. Have different conductivity rates of both electrical current as well as heat transfer which will need to be preserved or maintained despite the processing (often that is difficult to achieve). So there is a ton of additional costs.
Nowadays you have a whole bunch of these “mini rocket” companies popping up everywhere with various ideas, most of which are started by regular business people not familiar with what it is that they got themselves into. As a result, vast, and I do mean vast majority of them go belly up relatively quick (around 80-90% business failure rate), very few survive. You can easily verify all this by doing some more advanced searches and build yourself a nice list of who and what and why has failed and who and why and how succeeded. This is important as it will give you a good idea to compare to what you have in mind and an excellent reference for going forward.
Hope this helps you out a bit.