Fused filament fabrication (FFF) is an extrusion-based additive manufacturing process, which is very popular for the fabrication of polymeric parts with complex geometry. FFF can be used as an economical alternative for the production of metal parts, too, by using filaments with a volume content of metal powder greater than 50 vol%. The additive manufacturing process must be followed by a debinding step and a sintering step. The addition of metal particles to matrices usually used in FFF makes the filaments brittle and non-flexible; therefore the extrusion process during FFF is hindered. In order to overcome the brittleness a special polymeric binder system had to be prepared, consisting of flexible and stiff components. With this matrix and 55 vol% of three different metal powders – stainless steel, titanium and a magnetic alloy of NdFeB – filaments were produced and their tensile properties were tested. The printing trials, performed on a conventional FFF machine, proved that all of those materials were still printable even though their tensile properties were very different. The printed parts were debound with a solvent and after sintering metallic parts were obtained.