As with all framing, the frame and mat need to work well with the art, without stealing the show. Sometimes just 1 simple line can dress up a project just enough, without overwhelming the art. Other times a more elaborate design can really accent the art. In design, French Mats are used to liven up a simple piece, create an antique look, accentuate a particular color scheme, add visual interest to a large border and to dress a piece up.
Designs can consist of simple lines, wash or painted panels or drawn in motifs, such as ribbons, garlands, geometric patterns and flourishes. Lines can also be embossed by using a stylus to scribe an invisible line, called a blind embossed line. Materials used, range from watercolors, gouaches and inks, to powders that are rubbed into the surface of the mat board. Colors are usually pulled from the art and subdued so that they aren't as bright as the art, but marbled or gilded papers, which are much bolder, can be cut into strips and applied with glue to create narrow bands of color. The art, personal taste, and frame will dictate how elaborate the mat should be. You are only limited by your imagination, tools and materials, and pocket book.