Dummy is a mock-up copy of your book or packaging by using same paper, binding (for books), and structure (for packaging) following the specs as per your request. For some simple projects, we offer free dummies and the only cost you would need to pay is courier. But for a softcover dummy that requires smyth sewn, lay-flat binding, or a hardcover dummy and a rigid paper box dummy, there would be a sample cost excluding the courier cost.
Here are image references of dummies for some books and rigid paper boxes:
(A lay-flat softcover book dummy)
(Dummy for a set of 24 softcover books and a book holder with EPE foam)
(A challenging dummy for a softcover book with hollow interior pages glued with a outer case)
(A "standable" magnetic rigid box dummy)
(A dummy for a cardboard box with tray)
(A dummy for a magnetic box with mirror and bulbs inside)