This will work for any rectangular piece of paper, including wrapping paper scraps or gum wrappers, as long as it is actually a rectangle, ie. has right-angled corners. Or at least has two right-angled corners. The tag end can be folded over and torn off, as it might get in the way of clean folds, especially if your square turns out to be very small. (/me likes to leave little cranes wherever hands have been free..)