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

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