Does the Rebel Alliance have a manufacturing base?

Question

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.

Answer 1

There are such bases, but they might not belong to the Alliance

We know that there are installations where Rebel ships, such as the X-wing, are produced:

The Rebellion built its T-65 X-wings in hangars and drydocks hidden from Imperial spies.

_{The Force Awakens: Incredible Cross-Sections}

However, the X-wing is known to have been designed (and perhaps built) by Incom. It’s not clear how we reconcile the X-wing’s being built by the Rebellion, and being a product of Incom.

A possible clue is given by the production of B-wings:

JUN SATO: It seems Senator Organa has found a ship works sympathetic to our cause, and willing to manufacture more of these B-wings in secret.

_{Star Wars: Rebels, “Wings of the Master”}

This manufacturer was presumably Slayn and Korpil. As such, perhaps Incom was another Rebel -friendly manufacturer that produced X-wings in secret.

Answer 2

Capital ships:

Mon Calamari is the main source (including in Disney canon), excluding Corellian corvettes. "Rogue One" novelization notes that Mon Cala was building the ships to aid the rebellion, and the admiral knew that Death Star would be used to punish them for this.

Mon Cala had resisted. Mon Cala had been punished. Mon Cala had, time and again, offered its warriors and resources to the Rebellion.
If the Rebellion failed to stop the Death Star, Mon Cala would be obliterated. For this reason—and for a hundred others—Raddus would fight as long as the Profundity endured.

Fighters

• Incom built X-Wing prototypes, including in Disney canon. Most X-Wings after that were built in "Alliance facilities" as per Legends canon ("Empire at War"), after The Empire took over Incom Corporation around the time of the Battle of Yavin because of prototype transfer.

• B-Wings were manufactured "under the covers" by Slayn & Korpil corporation according to Rebels