IronFill PLA is a mix of standard PLA with iron powder. Ironfill is magnetic and it will rust like standard raw iron.
Ironfill filaments prints like plastic, but can be finished like real metal. It is relatively easy to work with and does not require a heated bed. Many finishing options are possible:
Rock tumble with steel shot for darker, but smooth/shiny look
Paint part with spray ink (black for example) to fill recesses with a contrasting color and sand away the surface.
Polish with a rotary tool, cotton buff, and polishing compound for a bright, mirror finish on high spots (darkens low spots)
Polish with paper for a clean, smooth, and bright finish with less darkening
Use Wire Brush to expose metal for future oxidation or a bright, satin finish
Patina (oxidize) exposed metal naturally or accelerate with a 50/50 vinegar/hydrogen peroxide mixture saturated with salt. Place in sealed plastic bag to retain moisture. Heat further accelerates reaction.
Ease of Use
Sticks too well to acrylic, use hair spray or glue stick.