I think that you might have trouble extruding recycled plastic in the small filament sizes used by most 3d printers. I think this because I read that extrusion doesn't always work well without filament grade (high quality) plastic.

However, if you extrude the recycled plastic in a larger size then I think that it should still work ok. Google "university of washington 3d printed kayak". You will find a story about a group which 3d printed a kayak using recycled plastic. One of stories mentions that larger sizes of plastic don't clog as easily.

Then again, I'm not an expert.

Lots and lots of experience documented in the Filastruder subforum, but please keep discussion of your design limited to this thread in order to keep things organized.

I am building a Filament Extruder with ABS waste plastic directly distributed from a local waste disposal company. Are there any experiences with these materials? It seems that I need much more power for the auger, because the material is not round like pellets.

Here is my blog deltaprinter.blogspot.co.at/p/filament-extruder.html, where you can see images of my machine and the plastic I am going to use.

Thank you for any hints...