The other method of holding odd shapes is with 'darts'. You take a bamboo skewer or toothpick and tie a piece of dental floss on one end. Then you fold your curved line into a straight one, place the dart beside it, and use the floss to loop around a couple of times and tie it off. The wood keeps the folds from bunching up, and the floss allows for a fine, tight, resist. You can also initiate the reaction in a microwave (if that is your bag) as you have no metal stats to worry about...

BTW- I love this site! People these days part with tribal lore that used to be closely-held secrets. w00t!