Such craftsmanship is quite possible for firearms. During the Wild West there were a number of such gunsmiths that had near legendary reputations. Even today, small companies create incredible variants on mass produced firearms. Just check out the Beowulf .50 caliber M4 rifle.

When I meant manufacturing base I was referring to near-future style weapons like lasers or rather, more likely "plasma". Circuit boards require etching tanks, essentially large vats of acid to work on sheets of silicon (glass) glazed in copper. Microchips are even more insane, with billions of tiny transistors pressed into an incredibly unbelievably small form factor.