How to "make" Plastic




I have always searched for a quick and simple way to make plastic. I have tried many but the one in this instructable the best I have found. It uses materials that you probably already have in your house,
it is fun to do and can be completed within minutes. I hope you will enjoy doing this instructable and will be able to learn something at the same time.

Step 1: Materials

Acetone is commonly used as a paint thiner and can be found at your local hardware shop or at

glass container
This can be an empty pot of jam or a beaker.

expanded polystyrene (styrofoam)
You can buy styrofoam cups or use any other piece of styrofoam you have.

safety goglesYou might consider using these because acetone can cause permanent eye damage.

Step 2: Prepare the Acetone

Open the canister of acetone and pour some acetone into the glass container. You don't need much, 1 centimeter should be enough for a little batch of plastic. If theres not enough you can always add some more later.

Step 3: Melt the Styrofoam

Start by breaking your block or blocks of Styrofoam in pieces that fit into your glass container. Then take the pieces and push them into the acetone. Continue pushing Styrofoam into the acetone until the blocks you put in don't melt anymore.

Then wait one to five minutes for some of the acetone to evaporate. Wait one minute if you want it to mold the plastic and five if you want to shape it. The more you let the acetone evaporate the more solid it will be. You might even want to mold it while its still "liquid".

Here's a video that demonstrates the melting process.

Step 4: Other Usefull Info

If you do not use the plastic immediately cover the container in which you put the plastic.

If your plastic becomes to hard to work with dip it in some acetone to make it soft again.

The plastic fully cures in about 12 hours.

Step 5: Safety

Acetone is a very dangerous chemical, read the safety instructions before using it. You should never drink or inhale it. Also, do not do this project near any kind of flames because acetone is very flammable. Wash your hands after touching the uncured plastic or the acetone and don't do anything stupid. Do this project in a well ventilated area, preferably outside.

Here's an extract of the MSDS safety sheet: "May be harmful by inhalation, ingestion or skin absorption. Irritant. Liquid may cause permanent eye damage (corneal clouding). Contact with skin may cause defatting, leading to irritation. Long-term exposure may cause liver damage." Wearing gloves is a good idea, but you'll have to use butyl rubber gloves or some other kind of acetone resistant glove. For more information on chemical resistant gloves follow this link.

Disclaimer: I am not responsible for any harm done to you by your negligence or misinterpretation of this project and by using this information you agree to defend and hold me harmless from any and all claims, demands, damages, costs and liabilities.

Step 6: The Science Behind It

Polystyrene is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry.

The chemical makeup of polystyrene is a long chain hydrocarbon with every other carbon connected to a Phenyl group.

Expanded polystyrene (Styrofoam) is produced from a mixture of about 90-95% polystyrene and 5-10% gaseous blowing agent, most commonly pentane or carbon dioxide.The solid plastic is expanded into a foam through the use of heat, usually steam.

Pure solid polystyrene is a colorless, hard plastic with limited flexibility. It can be cast into molds with fine detail. Polystyrene can be transparent or can be made to take on various colors. It is economical and is used for producing plastic model assembly kits, license plate frames, plastic cutlery, CD "jewel" cases, and many other objects where a fairly rigid, economical plastic of any of various colours is desired.

When Styrofoam is added to acetone (a common organic solvent) it very rapidly dissolves, making it look like it is disappearing. The melted plastic can be recovered from the acetone to make hard solid Styrofoam plastic (polystyrene). In other words, you don't actually make plastic you just transform an existing form of plastic. The acetone sort of serves as a molecular "lubricant" between the polymer chains, allowing them to slide around each other. The Styrofoam becomes soft, releasing the air bubbles trapped in the foam, and the polystyrene ends up as a soft blob in the acetone. When the blob is removed and the acetone is allowed to evaporate, it solidifies into a piece of hard plastic.

Their are two type of solvents, polar solvents and non polar solvents. Bio-plastics will dissolve in polar solvents like water, while polystyrene will dissolve in non-polar solvents like acetone.

Let's consider two solvents that are pretty different in their polarities in order to explore this topic. Water, which we said is a polar solvent, dissolves almost anything that is polar, such as salt and many other ionic compounds. Water can't dissolve everything, though. Try removing fingernail polish with water and you'll see what I mean. Acetone, a solvent with some non-polar properties, is commonly used to do that job. Acetone is an effective solvent for all sorts of non-polar substances.

The resin identification code symbol for polystyrene, developed by the Society of the Plastics Industry so that items can be labeled for easy recycling, is 6. However, the majority of polystyrene products are currently not recycled because of a lack of suitable recycling facilities.
Hence, even tough this is a petroleum based plastic, you probably are helping the environment since you reuse a plastic that would usually go to waste and that would take thousands of years to decompose.

source: wikipedia

Participated in the
The Instructables Book Contest



    • Colors of the Rainbow Contest

      Colors of the Rainbow Contest
    • Classroom Science Contest

      Classroom Science Contest
    • Sensors Contest

      Sensors Contest

    328 Discussions


    Question 3 months ago on Introduction

    Ok, so I want to take the theory one step further. I want to create molded Styrofoam. I understand that I can melt the polystyrene in acetone. If I then grind it up, say using a sander, can I re-expand it in a mold. I am trying to make floating jigs for fishing and I cannot find unexpanded polystyrene anywhere for sale. Can I recycle the plastic to make my own?

    2 answers

    Answer 3 months ago

    I was thinking about this recently. It would be such a good way of recycling this commoly wasted/undervalued plastic. How to re expand it is impossible to find anywhere on the internet. My guess is maybe patent issues? Or maybe I just haven’t searched hard enough.


    Reply 3 months ago

    Ok, so I tried. It did not work at all. My problem may be my altitude. I over a mile above sea level. I was going to try and borrow a friends clothing steamer and see if I could get a higher temp to make the foam expand. I was also considering grinding into a finer powder to see if that helps. Anyone out there have other suggestions?

    I did find a cite talking about industrial expansion. They use steam at 200 degrees Celsius. that is two times the heat of boiling water. I have also considered a pressure cooker. I will post results. My wife is going to be mad about the instapot...


    2 years ago

    i have a 5 lb. bag of styrofoam beads. how much plastic would it yield?

    1 reply

    Reply 4 months ago

    5lb. (assuming lb is a measure of weight)

    the air in the beads has the same buoyancy as the surrounding air and as such wont contribute to the weight of the bag, so if you have 5 lb of PS you have 5 LB of PS, its volume will change tho, so if its 5 litres before it might be 5ml afterwards.


    5 months ago

    Sir i want to make any product by this way but wen aceton material poured in mould the air bubbel comes how to over come it


    Question 7 months ago

    Does it harden to action figure level hardness?


    Question 9 months ago on Step 6

    Is the blob safe to use after the acetone has evaporated? And is there a way I can test the blob to see if there is any remaining acetone?


    Reply 1 year ago

    easiest thing to do is add a black disposable #6 PS plastic picnic plate or solo cup. takes about a week to fully harden with acetone, depending on how thick it is, the eps dries out on the surface making the middles a little harder to dry.


    1 year ago

    Done this with gas-appreciate the reminder Acetone works, also appreciate the science behind it. I do lost wax jewelry and lost foam casting of metals. I wonder if this would burn out of a mold in a firnace cleanly like was as this would be easier to work with on small, detailed items.


    2 years ago

    Hi! This is an interesting project. It's been a while. Have you been able to make anything useful from this material?

    munir A chughtai

    3 years ago


    Very Good instructable, Its very nice would you pleas instruct me which chemical should i include in this for waterproof my shirt.


    munir Ahmed Chughtai


    7 years ago on Introduction

    i made some of this stuff recently and filled a short length of PVC pipe with it as a mold. the next day i pick up the pvc to find that the plastic had not dried and also the PVC was going soft! i think that acetone is a solvent for PVC but won't dissolve it. i will experiment more and let you guys know.

    PS. the pipe was standard 20mm plumbing PVC pipe

    3 replies

    Reply 7 years ago on Introduction

    Acetone breaks down and reconstitutes almost all plastics. You could also use Acetone and Legos. Acetone and any ABS plastics will cause the plastics to melt essentially. That's why the PVC was going "soft". If you had more acetone there it would have melted it and could have caused a very large mess. I wouldn't recommend this type of "plastic" for injection molding.


    Reply 7 years ago on Introduction

    it went only a little soft. i actually tried to shove this stuff(acetone + thermocol) into a paper mold but even though i had painted it with resin it tore. any suggestions as to mold it? also i want to make a look alike spartan spear for a costume out of 3/4 in CPVC piping but i do not know how to shape the blade into one. any ideas for molding this?
    please respond.