PA Framing ADF WhtCore 3pc Mat Blanks 16x20 Black Accent Design Framing Mat Blank 16"x 20" White Core Black 3 Piece Accent Design Blank Framing Mats are a good place to begin, especially if you have an odd size picture that you'd like to mat, you can cut the interior dimensions yourself and save some money You can also use them as a sturdy backing for a framing "sandwich" and even use then as a base for other art projects