Specialty Metal Filaments

Proto-Pasta's Conductive PLA

Volume resistivity of 3D printed parts perpendicular to layers: 30 ohm-cm
Volume resistivity of 3D printed parts through layers (along Z axis): 115 ohm-cm

Proto-Pasta's Ferromagnetic Iron-infused PLA

This filament contains powdered iron, so that it has a rough cast metal appearance when printed, but can be rusted to give an aged appearance. It also responds to magnets (neodymium recommended).
Prints with normal-to-cool PLA settings (190-210ºC). A heated bed is not required but can be used at 50ºC.
The material is quite abrasive as it prints, so it can increase wear on soft brass nozzles. You may want to print with Ruby Nozzles or Stainless Steel nozzles instead.

Proto-Pasta's Stainless Steel

This is a dense material that prints as easily as standard PLA but results in heavy cast-metal-looking prints that can be brushed, sanded, or polished post-print to achieve amazing results. Perfect for jewelry, costumes, props, figurines, crafting, robots, and more!
In an unfinished form, prints look like cast metal. They can be left that way, or finished through a variety of methods to achieve different results.
The material is quite abrasive as it prints, so it can increase wear on soft brass nozzles. You may want to print with Ruby Nozzles or Stainless Steel nozzles instead.