I used a board wrapped with a cloth and then streached some heavy duty aluminum foil around that. the board was cut to fit the profile of the tub. This allowed me to turn the tub on it's side and basicaly just fill the hole with melted ABS. let it stand for a week and the board just popped right out leaving a very good repair behind. some small bit of the foil are still stuck to it but I will sand it before repeating the process on this side