This tutorial shows you how to create a strong closer for wider milk cartons, utilising strips of card, narrow ribbon and buttons.  There is also a four button version of this, which has been used in the “A5 Triple Width Milk Carton” tutorial.

I have included a link to the A5 Milk Carton series documentation below, because information on the button closers have been included in that document.  (Refer to pages 5 and 6).