Here are a few of  my 29 completed Sumi-e on Bristol paper [4″X6″] in Strathmore Photo Frame cards, labeled and into plastic sleeve.  One card was compromised from being left out a long time ago…. oh well, cat foot prints happen!
The black cards I actually glued a 4 ish by 5 ish piece of card stock inside so the purchaser can write a note inside….

Photo Frame Cards

Dick Blick Art Materials has these on sale in the new catalog that came in the mail today.
White pack of 50 are $17.08 [prior price $35.29] p 28 card making or
It definitively makes it easier to display art although the mini paintings are cropped by the card.  Otherwise the mini original Sumi-e painted on sumi paper has to be adhered to the card stock which can cause wrinkle or in the case of the red card stock…. the color bleeds into the sumi paper.

The purchaser can easily remove the mini art easily and frame/mount the piece in/on something else.