https://www.youtube.com/watch?v=Wx7GugDZOx4 and https://www.youtube.com/watch?v=l-qAQ6kQWO0 pellet extruder instead of filament.
titan robotics 
Edit
https://www.youtube.com/watch?v=QB4HyC4gIDc
links Edit
Heated chamber hack the Stratasys patent with a Fronting company
