HDPE Shot Glass From An Oven

So a while back i got a hip flask for my 18 year old birthday
And with it followed a bunch of iron shot glass, that i immediately thought could be used as molds.
– And so began the experiment.


I collected a bunch of cut plastic in 3 color sorted piles, and melted them at a temperature of 180’C
(picture one)

2 to 3 times the plastic had to be taken out of the oven to be pressed together.
Then to be put back into the oven.
(picture two)

When the plastic started sticking together, i placed it in one of the iron cups and pressed another one down on the top.

Some kinda rough results but the ideea is there!
(picture three)

@s2019 I second that.

This is why I’m mosly looking at upcycling for food projects. Especially in Europe regulations can be murder as so far as to even just remove the idea of toxins coming near food.

A bit paranoid, but at scale a chance of 1 in a million happens at least 10 times a day…

I think this forum should have a sticky about (not) using recycled plastic for food containers, especially wet contact containers. A quick google of something like “recycled plastic food contact” brings up links to a number of regulatory sites on the topic. While a large company may be able to work their way through the requirements, PP using unknown post consumer plastic has little chance of meeting these requirements.

The question keeps coming up, perhaps there should be a more visible thread.

Thanks for your reply @imuh

You only worked with baking paper at the beginning? Is there a reason you stopped working with that?


Let me know please.

@chenkus i guess it’s baking-paper (that’s what i have been using at the beginning of my experiments)

hey ! though the idea of using these as moulds is awesome, i highly recommend you to do some research concerning additives.

<span style=”color: #313131;”>Plastics… so what is a plastic ? A plastic is : polymer + additivesThe polymer can be Polyethylene (PE), Polypropylene (PP) etc… each polymer has it’s own properties (density, clearness, softness etc…)

Additives on the other hand will give extra properties to the plastic. The types of additives are VERY wide, can be to add uv-resistance, strength, make it easier to inject, cheaper to produce, flame resistant, etc…

Each additive (at least in europe) is more or less regulated into big categories of products, the most strict category being “food grade”; the legislation only permits industries to select additives through their list (1000+ possible additives)

Also, additives always migrate, meaning they get out of the plastics through time, heat, contact… and each additive has a treshold which should not be exceeded (measurements are based on the usage of the product; single use plastic = 1 time use migration treshold measurement)

Soooo when you are putting one type of plastic to melt; there are different additives which may react to each other, and your long lasting “food grade” recycled plastic product will slowly but surely migrate its different additives to the consumerTo limit this effect i would recommend you to have an effective ‘sourcing’; meaning trying a specific product at a time and, if it goes well, put it on a green list; otherwise, red…

(What i wrote is just based on the research of have been doing the past year on the subject, making mistakes, learning from them and searching more & more, which might not be the case of everyone launching PP projects _to answer to the “food-grade” recycled products on the bazar_ ; if any polymer-specialist would mind adding their intel on the subject…  )

Here is a very interesting document that @marcvdv sent me concerning additives : https://www.sciencedirect.com/science/article/pii/S030438941730763X


Cheers !


Question: What kind of paper (?) do you put with the plastic in the oven?

burrs need to be taken

Looks pretty nice to say the least