Start with a 18 x 24 inch piece of paper .
Fold a set of side extentions from 2 x 12 in strips of paper.
Get two strips of 12 x 1.5 inch folded in half to make handles for the top.
Make two handles from 1.5 inch strips that are folded in half and glued flat. and 
Fold them into a "u" shaped position. They will look like the handled on brown paper grocery bags. Glue them to the top opening of the case.
This holds flat artwork with out folding it if the art papers are 12 x 18 inch or less.
