I've seen:
* Under glass on the counter
* One large frame with an array (n row,n columns) of various styles cut in it
* a number of wide single row frames (ie, three or four frames with a row of five openings each.) this is usually done allong the top of the display above the corner samples.
* A "book" of samples. This can take the form of a three ring binder with clear sleeves with a mat in each, A "pile" which is usually placed in an acrylic box of some sort, or under the counter to be pulled out when needed.
You can easily think of variations on the "book" of samples idea.
I actually have one of the old FramerSolution.com pattern catalogs that I use. Essentially a nice full color fold-up piece with the different openings in it.
Hey Wizard ... How about making one of those available with the machine?