Making a bullet is definitely more difficult than printing a plastic gun handle (you need the bullet itself, and the cartridge fit it perfectly), and you have a non-zero chance to lose some parts of the body if you make a mistake.
Lead melting is not difficult. The brass case you can just collect used ones.
The primer would be harder to make (you can buy them online ofc) but with access to fireworks it is possible with no knowledge of chemistry and no realistic risk of losing body parts.
The guy who killed Shinzo Abe didn't need any of these things and still shot him.
