<p>Can someone shed some light in why FDM (Fuse Deposition Modelling) is not possible with metals?</p>
<p>Has anyone attempted any experiments with it?</p>

For many metals you would need to run the hotend around 1000 °C.  Aluminum melts at a lower temperature but needs to be in an inert atmosphere, such as argon.  Solder melts at the right temperature, but tends to stick to most metal nozzles.  It would start dissolving a brass nozzle thus enlarging the nozzle opening.  Lockheed has a titanium alloy printer that melts powder with a laser.  I would assume they need an inert atmosphere since titanium reacts with nitrogen as well as oxygen.