There have been a number of these shops. Khyber Pass as an area is famous for gunsmithing. Many of them work in the same little shacks they live and sleep in, crouching on the floor without a bench. A tremendous amount of work is done with just hand files and anything above a bench grinder is rare, although mills and lathes do exist. They make everything from cheap pistols to high end, blued FALs with gilded walnut stocks. I have even seen pictures of of them priming ammunition with a bench block and a small hammer
There was also a video I saw of some illegal gunsmiths in the Philippines who specialize in making guns with counterfeit factory markings that pass for factory guns. They make 1911s by welding large blocks of metal around a jig and drilling the holes to location, then hand filing. 3 of them working 8 hours a day or more will produce 5 or 6 guns a month. They're then transferred to the city of Danao. A friend of mine who moved here from the Philippines in college tells me that these handmade guns are widely known and are actually called
danao after the city they are popular from.
There's also the pictures of the Syrian rebels creating platforms to mount captured aircraft cannons on the back of pickup trucks, and the bomb makers smoking in the basement next to live munition.
