I tried this for the first time myself just last night, and I have to admit that it's alot easier than I thought. Here's how you do it...
1) Take a piece of sprue of sufficient length that if heated in the middle, you won't burn your fingers.
2) Place heat source (I used my Zippo) on flat surface, free of combustables and light. Candles work great, plus you get that pleasant smell.
3) Gently heat the piece of sprue in the middle, rolling it to ensure even heat distribution. When plastic becomes slightly pliable...
4) Remove from heat and gently pull on ends of sprue, using a slow, even motion. The plastic should "thread out" in a fine string. Continue expansion until desired thickness.
5) Maintain a slight amount of tension on sprue ends until hardened (about 10 seconds), then trim to desired length.
Give it a shot, you might be surprised at the ease of it. Good luck!
demono69