Interesting Instructable on Making Blocks of HDPE

I came across this instructable for using recycled containers to make HDPE blocks and I was wondering if anyone here has ever tried this:

He uses the technique to get some unusual patterns and colors and it seems like it might be fun to make stuff with it on the Shapeoko.


If one could find a true flat big enough one could make a true “waste” board for any SO3, or mill it down.

Yeah, did that for my SO3 when I first got it:

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Yeah, I used that process to make small parts for some of the toys. I had a real problem with the fumes. There’s not suppose to be fumes if you heat it to 350 degrees but I sure had head aches from the fumes even after moving the toaster oven outside. Gave it up because of that , you also have to heat up the blocks for pressing flat to do it right. The parts were fine and came out of the molds fine, just the fumes and the huge hassle of cutting up the bottles, I also melted plastic grocery bags but you have to cut out all the seams to not trap any air. The trapped air does not just “rise” to the top through the melted plastic, just little hot air balloons that will pop at the wrong time. Big blocks may be easier and worth the effort but that just increases the cutting into small pieces hassle. If you get it to the melting (liquid) state than you are very close to the flash point and there is no stopping the heat rise at that point. The resulting black smoke is no fun. Like most stuff on the internet, someone else’s apparent success always cost more than they express. I doubt anyone’s wife would appreciate cooking plastic in her oven. At the engineering office one of the engineers heated up some samples (from the waste water plant “poo”) in the break room’s microwave and the secretary made him buy a new microwave. And it does take a lot more plastic bottles than you think it would. YMMV, mine didn’t. Good luck, Jude

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Check out the open source machines on this website.

Dutch engineer has put a good amount of effort into designing them.