Slow cooker

I just had an idea, could we use a ‘crock pot’ style electric slow cooker to melt plastics? You can set the temperature quite precisely and the mould could be made to fit exactly to the inside of the pot for best heat transfer – see my other post on plaster of paris moulds?


Alternatively just to melt the plastic into a dough to be pressed into a separate mould…

Take a look at this thread for some additional ideas . Especially the video posted by @andyn . The combination of the cheap PID controller/SSR and a couple of very low cost cartridge heaters gives you a lot of flexibility for experimenting. If you already have the slow cooker, measure it with one of the IR thermometers. I probably has poor control and 250 degrees F may be too low. but both of these can be addressed with the extra controller and heaters.

Unless the part is very small, I think you will need more than just a heavy weight to press the part well enough to get the voids out.  If you don’t use a press, some provisions for clamping will help.

Just checking (about the videos etc.) 😉


I totaly get it.

It’s not that different for me, but the conclussion I reached was that it’s easier to ‘go with the flow’ than to start experimenting myself, in orders of effort (in orders of fun I experiment 🙂 )

The only way to find out if the ‘crock’ method would work, is to build and test it yourself, if no information can be found on the forum.


It’s a ‘chicken and egg’ situation (let’s not make it a catch-22).


Correct me if I’m wrong though, but did you not already 3d-print the PoC?


There are a lot of smart and capable people in this community, starting with Dave.

If there were an easy way to do this, it would be on the front page.

I’m however affraid all that can be done is melting ‘the hard way’…


Hi Donald,
yes I have watched the videos and I have been researching different ways to produce a product which I have in mind. At this stage I just need a proof of concept of the actual product, not the production method, so I don’t want to commit to building a machine yet.
From what I can gather, some crock pot slow cookers on the highest setting can reach around 250deg Fahrenheit which I believe is just about hot enough to melt HDPE. I do understand that the thermostat and temperature sensor need to be replaced in order to maintain a stable temperature but I think this should be possible. One advantage would be that the pressure could be delivered by simply placing a heavy weight on top of the mold.

Hi @timberstar,

Have you researched the building plans and/or watched the instructional videos?

They answer a lot of these questions. Maybe not directly, but they do touch on a lot of related subjects (like how to prepare the oven to be useful).


BTW, it would not be a slowcooker, but a frying pan, if it could reach temperatures high enough to melt the plastics 🙂

And yes, you can “set the temperature quite precisely”, but the actual temperature would be all over the place and not precise at all.

And thats just for starters 😉


That being said, you could make chocolate bars this way !


Always stay curious, and there is no such thing as a bad idea (only acting upon them may not always be smart).

Like me, you can find most of this kind of information in the instructions/videos or by searching the forum.

Melting plastics requires higher temperatures than what a slow cooker can typically reach, and the process can release harmful fumes that are not safe for food preparation.

In addition, the use of a plaster of Paris mold may not be suitable for melting plastics. Plaster of Paris can crack or break under high temperatures, leading to a faulty mold and a failed project. It’s best to use materials specifically designed for creating molds for plastic, such as silicone or high-temperature resin.

As a suggestion, you can cook corned beef in crock pot, beef stew, or beef joint instead of melting plastic. I know my suggestion sounds funny, but melting plastic at home without special equipment and proper knowledge is dangerous. It’s crucial to take safety seriously when working with high-temperature materials to prevent injury or harm to yourself and others.

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