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Does anyone know an adequate way to melt plastic for pouring into molds? Answered

I've tried in a pot with some oil as a quasi-solvent/medium and also a double boiler; both end up with a "goo" that is almost impossible to work with. The type of plastic is #2HDPE and #4LDPE. I have also tried a hot plate and a propane burner; both ways also yeild the same results.


Instead of melting your own plastic (and exposing yourself to potentially dangerous fumes) try an epoxy resin mix.

Try Smooth-On:

They have a multitude of products to meet any need.  Also it is a simple two part mixture that is much easier than measuring out catalyst.  Just mix equal amounts of parts A and B, pour into your mold, and wait a few minutes.

3D printer problem solved

Buy the right kind in the first place.  Pourable plastics generally fall into the epoxy types (two part).  If you want details, you need heat and pressure (positive or negative).  In other words, hot plastic, hot mold and push or pull the plastic into the details.

The stuff that oozes out of injection moulding machines is thick like toothpaste. The stuff I saw was polypropylene though.

Have you thought about vacuum forming?  If you can get the plastic in sheets large enough and your shape lends itself to vacuum forming.

Most plastics that are poured into the mold are 2 or 3 part liquids that are mixed like epoxy then poured while liquid and set up or cure in the mold.  Even the liquids have to be pumped into a complicated mold though.

Its usually blow or injection moulded, because its too viscous to pour.


You dont usually pour plastic, like zinc you force it into moulds from a closed-system. So to answer the question , no.