if you can get ahold of any graphite powder the fix will be much better aesthetically,
mix w epoxy to the thickness of peanut butter, sand first, tape box around damage, fill, let harden, sand flat using a sanding block and wet 220->400->600
West Systems Graphite Powder :http://www.jmsonline.net/filler-graphit ... oCMKLw_wcB
Mix it with a SLOW cure Epoxy , (NOT polyester) ; the slower the cure, the
better the bond.
Do NOT use bondo ; that is also a polyester.
On a molecular level, Epoxy has a molecular weight chain that is Much smaller
than that of polyester ; so the mechanical bond of epoxy is MUCH BETTER
than if you fix the same with polyester. It would be like poring sand, (your epoxy)
to fix your foil ; or using a binder that has molecules the size of gulf-balls, (your polyester).
Remember that your foil is Already cured, so the bond with your fix is mechanical
in nature ; not like a molecular bond you get, between un-cured layers of resin, when
your laying down freshly wetted-out fibers.