Printer components for costumizing firearms, is it legal?

Hi,I just want to know whether it is legal to print components for firearms or not (for costumizing the weapon). I am very interested in the subject, anyone interested as well can contact me by my email: panincicperun@gmail.com Regards

in the us as long as you don't change the lower receiver - I think you can change anything else.
Any printed firearm components are probably illegal in the uk.
no clue about the rest of the world :-)