Two years ago, Dick Plasschaert was a struggling artist working in a printing plant in Waseca, Minn. Then the federal government made him a wealthy man.

Plasschaert painted the Mona Lisa of duck portraits -- a pair of mallards that the U.S. Fish and Wildlife Service chose for the 1980-81 duck stamp. For 32 years, the Department of the Interior service has run contests for a waterbird stamp design, which duck hunters must buy for licenses.

Plasschaert is now a full-time artist in Waseca, living in a house bought with part of the $500,000 profit he made after winning.

The service only gives the winner a sheet of the $7.50 stamps. But winners have sold limited-edition prints to collectors, parlaying victories into fortunes and new artistic careers.

Plasschaert sold 12,950 prints for $125 each. And all his other work, past and future, instantly became more valuable.

Until recently, only 400 to 500 people entered, according to a service writer. But last year, more than 1,500 people submitted their work, and the deadline for entries has been moved up two weeks, to Oct. 1, to give the five-judge panel more time to sift through designs.

Revenue from the stamps is used to purchase marshland for waterfowl, so far nearly 2.5 million acres.

How to Enter: Request an entry form and contest rules from: Audio-Audio-visual Office, U.S. Fish and Wildlife Service, Room 8070, Main Interior Bldg., Washington D.C. 20240. Color or black and white designs, 7 inches wide and 5 inches high, may be in pen and ink, oil paints, water color, etching or pencil. CAPTION: Picture, Artist Dick Plasschaert's winning duck stamp design has earned him about $500,000. U.S. Fish and Wildlife Service