WHEN HE was 3 years old he started drawing faces. By the age of 7 he was making little heads out of clay or wood or soap or whatever was around. Now Maceo Jeffries is 40, and he supports his wife and two children with his sculpture though he has never taken a lesson in his life.

He could give lessons, for that matter.

"I don't know, I just see it," he says. "I look at a photograph of a man and I know how he looks in the back. I see him in three dimensions. I feel like it's a sort of spiritual thing."

He is making a life-size Jesus for the First Superet Branch Church of Washington, replacing another statue that broke. He doesn't bother with sketches or small models, he simply sets up a frame and a piece of 4-by-4 in the yard beside his house in Riverdale, and starts slapping clay on it.

The Jesus took a year, and now it is covered with rubberoid material from which he will make a plaster cast. Eventually it will be done in concrete and possibly bronze as well.

"Some nuns from the church came around to see it, and they knelt down and said a prayer. They said they felt a lot of energy in this home."

He makes it all seem so easy. How do you get the muscles right for a running figure? "Well, I look in the encyclopedia, there's a drawing with all the muscles and their names."

How did you learn to cast sculptures in rubber and plaster and all? "Well, you just buy the stuff and read the instructions on the box."

Born in Duquesne, Pa., he enlisted in the Army after finishing high school, found he could always get a job as company draftsman, artist and postermaker. He concentrated on drawing during a hitch in Germany, and when he got out in 1965 he moved to Washington and did drafting work for civil engineering firms on water-sewer projects.

In '76 he declared his independence, began working full time for himself. The first commission he got was for a platter-size bronze plaque that graces the executive offices of the World Trade Center in Baltimore.

All around his living room, where he works unless the piece is too big to get through the door, are small sculptures of animals and people, large portrait busts of Martin Luther King and Tutankhamen, rings and belt buckles, plaques and novelty bottle-stoppers. He can carve a scale model of a building from wax, cast it in bronze or brass or whatever you want. He has made little abstract football-player figures for a game manufacturer. Almost finished is a large plaque with a portrait (taken from a photo) of William Earl (Bill) Vines, the first black deputy sheriff of Pitt County, N.C.

"I'll take any commission I can get," the sculptor says. "I went to the people at Lorton with a proposal for a plaque of Delbert Jackson, and they loved it--if they can raise the money."

When he's not working on commission, Jeffries likes to make little figurines from pictures. He has done a marvelously realistic set of prehistoric beasts in clay. A miniature bust of a pharaoh in soft dentist's clay might take four hours, half a day's work. Or he might carve a tiny portrait in soap for his wife.

Michelangelo was supposed to have explained, when asked how he made his statues, "I just cut away the parts I don't want." Simple.