If you want companies, I suggest picking the most known and those that had most impact in SW stories. Let's see:
Sienar Fleet Systems (formerly Republic Sienar Systems) - TIE fighters
KDY - As said, Star Destroyers. There's many capital ship manufacturing companies and quite a few shipyard worlds as well, however.
SoroSuub - The Sullustan corp. They manufacture all sorts of things.
CEC - All sorts of correlian ships. Freighters and smaller capital ships.
Tendrano Arms - Lando's corp. Most famous for the YVH 1 droid. Starts to get significant in stories only in NJO era and later, tho.
Czerka - Big corporation in KotOR. Shrunk into a smallish weapon manufacturer in the later eras.
Incom - X-wing and some shuttles too, but mainly the X-wing and its precursor, Z-95.
TaggeCo - Run by Tagge family. Caused some trouble for the heroes in 80's comics. Mostly mining, I agree.
BlasTech - A lot of famous blaster models. Han's DL-44 and stormtroopers' E-11's for example.
Didn't Arakyd make warheads too, at least concussion missiles?