If you drink milk at all, then your throwing away some easy to recycle plastic that you could use of other projects. Start collecting them, and you'd be surprised how soon you'll have enough to make your own brick of plastic. This is the number "4" type plastic.
Step 1: Fondue Melt Pot
I've had this fondue pot taking up space in my closet for such a long time that I finally decided to re-purpose it to my melt pot.
Step 2: Now for the Caps
After removing any paper label with a razor, you can start throwing them into the pot. I turning the heat up to 300deg F. to let them slowly melt flat. If you turn the heat up all the way you could chance the plastic burning on the bottom.
Step 3: Cooling
If your pot is straight walled enough the plastic will shrink enough to come out without any effort. I baked my first batch for about 20 minutes. The end result was a plate of plastic about 5/8" thick. I have more caps, but I need to remove those stick on labels before I throw them into the pot. The best advice I can give it to bring up the heat slow and wait for most of the bubbles to surface before you turn off the heat. Trying to pour your plastic into another container won't work as well, because the plastic will start to harden before you've even finished pouring.