Hot glue is a baaaaad choice, molten hot glue + card + fingers is always going to lead to pain. Hot glue is fine for foam, but for card, there is just not enough material between fingers and the glue. For pepping a regular multi purpose glue or a paper glue works fine. Hot glue also dries too thick and is too rubbery. Also, when resin is curing it produces heat heat softens hot glue, this can lead to imperfections.