Protopasta Rustable Magnetic Iron PLA vs Protopasta High Density Stainless Steel HTPLA

Both are metal-filled Protopasta filaments that print with a matte, cast-metal look and respond to magnets. The Iron PLA is the easier, more forgiving choice for decorative artifacts and rust effects, and it comes on a full spool. The Stainless Steel HTPLA carries a 70wt% steel load, is the more magnetic of the two, and can be heat treated for roughly 3x the temperature resistance, so it suits functional or heat-exposed parts. Owners of both report good first prints with a tuned profile; the iron is a bit more brittle and abrasive, and the steel needs retraction dialed in and can wear a brass nozzle.

• Choose the Iron-filled Metal Composite PLA if you want rustable, magnetic decorative pieces with a cast-iron look and a larger spool for bigger projects.
• Choose the High Density Stainless Steel-filled HTPLA if you need the strongest magnetic pull, a polishable steel finish, or heat-treated parts that hold up at higher temperatures.