[@6slyboy6] Well, I take it that Levi has some cache of bits and bops on his airship. Why not let them make their own gun, or let one character make other peoples guns. Make it a test for the engineer, to see if he/she can fit on Levi's ship. 
Or... you could always have the cache contain guns themselves and just skip the whole crafting part.
Another idea is that you just obtain them along the way, but each time it's only a few, and the crew has to decide who get's what.
So many ideas!