When I see pictures like this, it really freaks me out as I plan to mount my cold cathode in my trunk.

http://www.casemodgod.com/ccfl_inverter_rant.htm

If somehow the inverter explodes in my trunk, the trunk lining fibers will light up so fast. Should I build a small metal case to enclose the inverter? I think that might cause it to heat up more though.

 

I have never heard of something like that happening in a car before. But if it helps, I believe Radio Shack sells "project cases" made of either metal or plastic. They are basically little boxes normally used for electronic hobby building. I think that will give you the piece of mind you are looking for.