The Swiss Guard has guarded the Pope's residence for centuries, and thanks to 3D printing, the world's oldest functioning army is getting a technological upgrade. Since the 15th century, the uniform of the Guards has remained essentially unchanged. One part, however, was in dire need of an upgrade. The heavy steel helmets were causing the guardsmen's skin to burn in the hot summer sun. 3D printing helped replace the metal with a plastic replica that is impact and weather resistant. Above all, it's lightweight and cooling thanks to the design of special ventilation channels. Moreover, the cost of producing one helmet on the HP Multi Jet Fusion 3D printer is half that of the metal version. Thanks to the contribution of private donors, over 40 helmets have already been produced and another 60 will be printed.