Step 6: Finalization
Method 1 - Resin and Fiberglass
There are a few different tutorials online which I've found and this is the preferred method. Remember that resin gives off fumes so do this in a well ventilated area. Also wear thick gloves when working with fiberglass, it's pretty much glass that is thin like thread so if that goes in your skin = bad end.
Method 2 - Plastic Casting Compound
This method is safer, but a little more pricey. Smooth-Cast 300 is a two part compound that when mixed together becomes white hard plastic so use this on the inside of the helmet.
I still have to do this final step.
Other than that I can't think of anything else more to say so have fun and be safe.