I am wondering if anyone has used "ULTEM" for their spark plug insulator? Im working on the kerzel H&M engine chose this material over Corian. it machines very well and is a little stiffer than Corian, has good insulating quality's too. I made my plug out of it and it seems to be working very well. just wondering if anyone else has tried it...a 3/8" rod 1' is about 6 bucks from mcmaster.