Using the product Instamorph to make an almost-perfect sphere. A 16 dollar package contains 87 fluid ounces.
Step 1: Step 2: Melting the Plastic
The product recommends a temperature of 140 degrees in water. This is not required. You can use any source of heat (preferably in water to avoid sticking to surfaces). The hotter the water you put it in, the faster it will melt and become moldable. When trying to reheat these objects, it will heat up quicker when shaped flat.
Step 2: Step 3: Molding
When you have your piece of plastic, find a flat surface that is clean. Then start to mold the piece into a shape that looks closer to a sphere. Don't press to hard when rolling the ball on the table, or else it will shape incorrectly. Remember, these steps are optional, you can do whatever you want to make a sphere with your plastic. That's all there is too it.