RF Welding! That's the phrase I was trying to remember, I remember seeing it in one of the trades years ago. I forwarded it to my customer, but I suspect I'll be doing the ordering and application for him. Thanks again everybody, and have a great New Year. In fact, my first screenprinting job was printing plastic phone book covers with ads on them, and part of the process was sealing the cover to the pockets with an RF die, Thermotron I think was the name. It had a vacuum tube in it about the size of a head, and cost about a grand in 1973 dollars...
Steve