For the definition of a Mavinian Deck of Cards, consult the Encyclopedia Hesberica here. In short, a Mavinian Deck is a five-suited deck of cards with twelve ranks in each suit. The top card is the Merchant. The next set of cards range from one to ten. The lowest card is the Servant card.
A group of people known as the Mavinian Traders use these cards for amusement as well as communication in their own language. Each deck is hand-crafted, usually by the person using a given deck. Many are crudely made with whatever material is at hand, but a few are ornately made with the Merchant and Servants cards drawn with faces.
On the downloads page you can download pdfs and an all-in-one zip file. Individual OpenOffice Draw files will be posted soon. These example files do not represent an ornate deck. Instead they will serve as a prototype deck for playtesting.
These cards are very close to Las Vegas poker card standards - 2.35" wide and 3.25" long. The corners are rounded with a 1/4" radius.