I'm going to tell you a little bit about ACEOs, since I paint them, I collect them, and I want to share them with you.
ACEO stands for Art Card Editions & Originals, They are miniature pieces of art. They measure 2.5" by 3.5" (the size of a baseball card). ACEOs can be paintings, drawings, mixed media, etc. The only rule is that they measure the correct size. They are considered collector's items, and have gained in popularity in recent years. They are a great way to obtain works of art at a fraction of the price of larger pieces. They can be displayed in frames or in albums.
I sell my originals and limited edition prints on eBay. Here are a few examples: