Try this page: http://www.shopmaninc.com/kk121.html
It is Kleer Koat Epoxy table finish. I've used it on turned bowls, put
it on a picnic table & it seems to be holding. It's a clear two part
epoxy for table tops, the kind you see on bars where they put it over
pennies or other small items. I've had great luck with it but make
sure you read the instructions very closely. It costs about $45 to get
a gallon of each the epoxy & hardener. if anything would stand up to
what you want, I think it would.

Jim