Possible source of extrudable plastic?

I happened to come across this post:
Homemade plastic on Instructables

which describes melting plastic grocery bags into molds by gently heating in canola oil. It also mentions that by pre-shredding them, you may be able to get a finer texture. I would guess you could probably feed plastic grocery bags through a paper shredder just fine?

I know nothing of the details of the plastics involved & whether it would be suitable for extrusion, but I figured I might pass it along.

I saw that too. I was thinking stewed plastic could be used to replace the hardened wax in the Xerograph Mendel.

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