Finished dimensions are 13” wide x 13” tall, which is big enough to hold a pretty decent candy haul but still small enough scale for kids to carry easily. This pattern will show you how to make a darling trick or treat bag that is perfect for carrying around as they gather all those. Needless to say, it wasn't surprising when one unfortunate child accidentally tore open their plastic bag, spraying candy all over the floor. Halloween trick or treat bag pattern. Make an easy and cute diy trick or treat bag this halloween!