Modern CNC mills and such, and 3D printing of metallic objects, mean that The Weapon Shops of Isher is darn near being a reality.
https://en.wikipedia.org/wiki/The_Weapon_Shops_of_Isher
An interesting side note to The Weapon Shops of Isher is that the author, Alan E. Van Vogt, was a Canadian who wrote the book about 1950. It was copyrighted in 1951.
I suspect that the book was based on the practice and failure of Canadian long gun registration during WWII. The long gun registration was eliminated in 1945.
http://www.cdnshootingsports.org/briefhistoryofguncontrolincana.html
With a little more research, it turns out there were major gun control initiatives in Canada from the end of the war to 1951 as well:
https://www.saf.org/journal/13/Off-TargetGunControlinCanada.htm
Further firearm legislation was introduced during the “red scare†that followed the war. In 1951 the government introduced the registration of automatic firearms.