I can second Jamestown, have used them for locally difficult to find things. I used to recommend Painter's Supply on Santa Fe for 3M but they have just about gotten completely out of stocking 3M and so I've gone to mail order out of sloth. There are several marine supplies around town plus Plasticare and ePlastic for just about everything in epoxy, resins and the like.
"Why does the U.S. care which flag will be hoisted on a small piece of land thousands of miles away?" -- Ron Paul