Metal Infused Filament: Protopasta Metal Filled PLA 3D Printer Filament is comprised of a base PLA plastic mixed with 45% by weight iron powder. This 500g spool of 1.75mm metallic composite filament has twice the density of standard PLA filament, making it perfect for prints requiring a metal look and feel. This iron PLA filament is also ferromagnetic, allowing magnets to stick to it. Multi-Purpose Metal Filament: Proto pasta printing filament is ideal for many different printing projects due to it's unique ability to have a patina for a truly metallic-looking finish. This lends a more realistic feel when printing models such as cars, tools, tabletop game miniatures, and other metallic accessories.