[Marvel] How hard is it to make an Iron Man-like suit, really?

Some random guy made whips that could cut through steel in a garage. There's a teenager out there who made two different supersuits for herself and fought Atlanteans with it.

I know that I'll never make anything on Tony Stark's level (I don't know how to even start making nanomachines), but if I was semi-knowledgeable about mechanical engineering, coding, and had my own box of scraps, would I be able to make my own Iron man suit?