In Star Wars Rebels, we see the Rebels having to scavenge, salvage and steal anything they can get their hands on to keep up the fight. Several episodes are based around stealing resources to keep themselves going. Alderaan is known to be funneling support to the Rebels, but they still have to stay covert and have the Rebels 'steal' the ships.
But at the same time, the Alliance has their own technology and ships - X-wings, A-wings, and B-wings are never seen in Imperial or pirate hands, and these ships can apparently be lost at a frightening rate without really affecting their ability to fight.
So does the Alliance have their own manufacturing facilities for constructing replacement X-wings? The prototype B-wing that appeared in Rebels was said to be being taken for production, but did we ever learn anything more?
Ideally I'm hoping for New Canon answers, but I'll take Legends if that's all we've got.