Its a pretty nice write up on how to re-use the failed prints as basically a board for a CNC. In theory you can do the same thing with HDPE. No so sure how well using a blender is for making the smaller bits thought.
http://www.instructables.com/id/Plastic-Smoothie-DIY-Plastic-Recycling/
And if you want to build a better shredder, check this build out.