Hello clshawks,
Anytime plastic is heated there is a chance of fumes. Its always a good idea to ventilate anything that changes the state of matter using heat. Even 3D printers should be ventilated because they melt plastic and give off fumes as well.
People have been forming plastic in their home for years even using their kitchen ovens for the heater source. One example is here: http://www.flickr.com/photos/doublellam ... 508593671/
http://blog.makezine.com/2007/01/30/vac ... ming-in-y/
You are using heat to melt plastic so you have to make sure you keep an eye on it and never leave it unattended. Keep a window cracked or use in a well ventilated area. The plastic should never touch the heating source in fact you are only trying to soften it for the pull, which takes only a few seconds over the heat source. I did a search on styrene fumes and found that it has to get extremely hot to release any toxic fumes. 300C - 572F
http://answers.yahoo.com/question/index ... 929AAYFBpb
Its still never a good idea to breath anything thats smoking. In future make sure you are right there watching the plastic so that it cannot sag and touch the hotplate. It should only sag about 1/2" at the max. Any more and it becomes unusable anyway.
Hope this helps.
Thanks
Mark and Trish

 

Welcome clshawks
Mark and Trish