Elaine,
there is the opportunity here to discuss how some stars are brighter, some are dimmer. This is linked to both how far away they are from us and how naturally bright they really are.
Would you offer different size and different point star shapes? Some cookie cutters come in different points, but 5 pointed stars seem to be the most common.
This could make an extra layer to the large Plough asterism that the children create, how would they represent the slightly brighter stars that make it up?