Ok yes you do need fiberglass resin and fiberglass cloth. I usually resin twice outside and resin and fiberglass ( meaning use fiberglass cloth dip it in resin and apply) but only after applying resin alone to the inside of the helmet. Then your will be hard enough to work on, meaning use Bondo for details. Don't want sound mean explaining steps but I just want to cover all areas you might have questions on. Good Luck