Any small clamps that will withstand torch flame without melting?

I'm going to be doing custom work to a pair of headlights. Normally I could bake the headlight until the glue softens up and then pull the light apart, but I cannot bake this set of lights apart so I will be cutting them open. To close them back up I plan on on using the speed welding technique, as well as coating the seam with some sort of weatherproof adhesive as its absolutely important that its completely water tight. My questions are, do you think this would be the best technique? What plastic do you think the clear plastic cover on headlights are made of? Is it absolutely necessary for me to match the welding rods to the type of plastic i'm welding? I was looking at the welding temperatures for a few different types of plastic, and some are 300C, 350C up to 650C+. Is it absolutely necessary to weld at exactly that temp, or is there some play? That would decide if I go with a cheap $25 heat gun, or a $400 variable temp heat gun. A few of the cheap ones are dual temp, at 300C and 600C, and im wondering if I can get away with this. Also, I will have to purchase a reducer to fit a speed welding attachment to the heat gun. Are the connecting parts of reducers and speed welding attachments all a standard size? Thanks for your help. Just as an FYI, the following is a picture of where I will be making my cut and weld [IMG]http://i465.photobucket.com/albums/rr15/primetimetsa/headlight.png[/IMG]

Afternoon everyone! New here, just had a quick question, hoping someone can help! Making some end tables, wanted to add the below accents to the steel, basically they look like rivets, does anyone know what they are? How do I get them and add them to my project? If they are rivets then that's cool, just wanna be sure... Thanks! Michael