All you need to do is run the die through your 'big shot' twice with thick designer series paper or cardstock, glue the two pieces together and fold up each of the four sides of the box.
These are coming to work with me tomorrow. I work in a village preschool and we have 17 children leaving to go to 'big' school at the end of term. They will each get a helium balloon and these boxes will be perfect filled with sweets and used to weight them down (until they eat the sweets!)
These boxes are 6.4 x 7 x 6.4cm and would also be ideal as wedding favour boxes or to hold a small gift.