This looks to be for creating filament. I see a geared DC motor, a nice big heat sink and what looks to be a heater block. Am I right in saying the cutout forward of the green gears is where the hopper goes?

The design is nice and compact. What I've seen of extruders to date relies on distance and a heat break, rather than having a heat sink, which means they're much larger than your design. Are you going to actively cool it?

I like the fact you're using a heating block. If my assumptions are correct, I think it will allow you much finer control over the heating of the plastic.

I can't see what you're going to use to force material through the machine. Is it custom-machined or a standard off-the-shelf part?

I can't see what sensors you have attached to this (if any). Will you be measuring filament width as it's extruded and fine-tuning heat/pressure to control it?