if you read the comments and stuff it says that the gun wasnt completely printed and only the lower receiver was printed. everything else is stock parts
well this is the first (known) gun printed that worked. i sure hope stock parts could attach to it, that is the entire point, to copy real guns.
it could have taken a month to print the receiver and assemble it perfectly. its not like the guy is a pro, its using a hobbyist-lvl home printer.
but if you can print the receiver of a gun, the most complicated part, then why wouldnt you assume the rails, grips, barrel would be harder to do?