PVC, polyvinyl chloride, is a thermoplastic. It softens with heat and rigidifies when it cools again. While soft, it can be bent and even stretched into molds. Cold, it can be sawed, filed, drilled, scraped, or whittled with a knife.
PVC material can be found at most hardware stores in the form of plumbing pipe. I find it to be inexpensive, especially when I consider all the things that can be done with it -- musical instruments, repairs, tools and toys to name a few.
It is resistant to sunlight damage, has a degree of flexibility, is fairly strong, and is electrically non-conductive.
This is a very valuable material for use in inventions; one that very few people seem to be have experience with.
The picture below shows some of the shapes it is possible to make with PVC.
Step 1: Safety While Heating PVC
We love plastics for what they do for us, but plastic manufacture and decay tend to pollute the environment and negatively affect our health.
Vinyl Chloride, one of the components of PVC, is carcinogenic. When it is locked up in the polymer, however, it is much safer to be around. In my years of experience working with PVC, I have not noticed any adverse effects on my health from being around it.
Always work in areas with good ventilation. If you do get caught in a cloud of smoke, hold your breath and move to clean air.
When heating PVC with a gas stove or propane torch, try not to let it burn. Smoke from burning PVC is bad. With experience one burns it less and less. Don't panic the first time you do burn some. It scorches, but doesn't immediately burst into flame. Move the material away from the flame and try again. Don't breathe the smoke. Smoke avoidance comes naturally for most people.
While heating PVC over a gas flame, keep the plastic an appropriate distance from the flame to avoid scorching the surface before the inside can warm up. It takes time for heat to travel to the center of the material being heated.
Keep the plastic moving, and keep an eye on the state of the plastic. When heated, the PVC material is flexible, like leather. Beyond this stage, you risk scorching it.
A word from James, the plastic engineer -- "Just a word of warning, PVC can handle some high heats but if it catches fire, you wont be able to put it out, it does not need oxygen to burn so don't do this inside".
I do work inside, but my house is made of cement and has good ventilation. MAKE SURE THAT YOU HAVE GOOD VENTILATION. PLAY WITH FIRE -- CAREFULLY.