Hi Joseph,
Again, really impressed with your enginuity !!!
But like the others, am confused with what you are trying to accomplish !!
If you are just glassing the foam, epoxy resin will cause no problems, what the other fello ment by resins desolving the foam, only accures if you use polyester type boat resin on styrofoam...
You can use polyester on polyurethane foam -- but be very carefull there as polyurethane foam can produce deadly fumes if hot wired -- while the styrofoam types work very nicely !!
The blue and pink foams work great and as you have seen, hot wire beautifuly but you must use an epoxy resin on them -- as someone already mentioned, a really good epoxy is "West systems" -- after glassing West systems has a filler, you mix with the resin to form a paste, that you can smear on the finished blades, that will fill the weave and is very easily sanded -- it is tan in color and is called "Microlite #410" -- very nice to work with..
Also was mentioned -- a spar !!
I have built blades without spars, by useing multiple layers of glass, but long blades, will flex -- a lot !! That is why I mentioned glassing in the carbon fibre arrow shafts in an earlier post..
If you want to make a mold, simply glass one of your blades, finish it to a glass like consistancy and use either wax or a mold release, called PVA (poly vinyl alcohol)
The problem then is , you need a two piece mold, as removing the blade after glassing is not fun or nearly impossiable !!
You do great work, have fun, Bill H..........