Nal also needs costumes for the "Cinderella", so she looks online and finds a website called 'Designer Costumes '. She sends an email to Peter saying she needs a dress for "Cinderella" that glow in the dark. Peter sends email back saying that he can do this for her - he just needs to know the size of the dress required. Peter also says, 'glow in the dark' material is extra expensive - I rarely use it and will have to order it in specially. Nal immediately writes back and says, 'please go ahead and order the material - I will provide the measurements the week before the production'. Nal also says, 'we don't have much time to get this all organized'. One week later, Peter rings Nal and says he has received the material, and unless he hears back from her, he will go ahead and start making the dress. Nal hears the message but ignores it as some mums from the school's 'Parents Association' have offered to make the costumes for free. Two days before the school production Nal remembers she hadn't spoken to Peter and rings him up to cancel the order. Peter is upset as he has nearly finished the dress and will not be able to reuse them.

what is promissory estoppel and is it relevant to Nal's dispute with Peter from 'Designer Costumes?