extruding metal?

I saw a youtube video of someone extruding solder into chanels whith a RepRap type printer. Would it be possible to extrude a metal by heating it enough to soften it, but not completely melt it? Or maybe have a cold bed so it solidifies on contact then the next layer heats the last just enough to bond?

Could layers of conductive paste or gel be extruded between layers of ABS to make printable electronics?

I was thinking something like the biomedical stuff available here: [bio-medical.com]