AS FAR AS RESINS, I'VE SEEN TWO DIFFERENT TYPES. THE REGULAR BOAT YARD STUFF, VERY INEXPENSIVE. THE 2ND IS WEST SYSTEMS 105. IT IS EPOXY SO I DON'T THINK YOU CAN GO BACK TO POLYESTER, BUT THE EPOXY STUFF IS KILLER. MORE EXPENSIVE BUT LOTS MORE STRENGTH!
YOU CAN PROBABLY LOOK THEM UP ON THE WEB, IT'S A REALLY IMFORMATIVE COMPANY. YOU'LL LEARN EVEN IF YOU DON'T END UP USING THEIR PRODUCT...BILL.