PERCY AND HIS MAGNIFICENT TIME MACHINE -- This Saturday at 1 and 3 at the Anacostia Neighborhood Museum, 2405 Martin Luther King Jr. Avenue SE (Metrobus: A8 or 94). Free. For information call 381-6731. For details on Tommy Duren's birthday shows, call him at 526-2597.

"Hi everyone, and welcome," says Pete, who introduces Percy, who finds a time machine -- a foil-covered box with a furry mouth. Percy, who lives in the 24th century, is thinking of quitting school because he's flunking black history. The time machine introduces him to Harriet Tubman and George Washington Carver, who talk him out of it.

Pete and Percy and the time machine and the people from the past all share the same voice: It belongs to a 12-year-old puppeteer named Tommy Duren.

"Usually, Tommy does all this by himself, but he hurt his knee playing football the other day," explained his mother, Jean Duren, wearing a Tommy's Super Puppets T-shirt. Before the show began, she was rushing around in back of her son's home-made puppet set at the Anacostia Neighborhood Museum.

As Tommy's mother and grandmother and grandfather walked around with extension cords and plugged in the tape recorder and the lights, the 12-year-old puppeteer hobbled around, taping the handwritten script to the back of the set and piling puppets on a table in the order they appear in the show. Tommy wrote the show, "Percy and His Magnificent Time Machine," at the request of the museum.

"I make most of the puppets," said Tommy, a student at Takoma Middle School. "I made Harriet Tubman especially for this show. I copy them from books, and also from what I personally think they look like. Some books make George Washington Carver look too skinny. I think he should mainly look old and very wise."

Jean Duren, putting rods into a rod puppet that later will dance to Fats Waller's "Your Feets Too Big," pointed to a rhinestone earring hung around the puppet's neck.

"Tommy found this earring on the street," she said proudly. "I give him all my sewing scraps, and he went into his baby clothes."

One puppet wears one of Tommy's baby shirts and another is dressed in his christening jacket. There are some rod puppets, but most are hand puppets.

"You can do more with hand puppets than with puppets that don't move their mouths," explained Tommy, adding that he is, however, also getting into marionettes and studying ventriloquism from a book. In some shows, he works four hand puppets at once -- two on his hands and two on his feet. This day, however, due to his knee injury, only two puppets will appear on stage at any one time.

"Do we have another extension cord?" asked Tommy's grandmother, as his mother hooked up the floodlight and Tommy put on some Scott Joplin tapes.

"This is a family project," explained Jean Duren. "I provide financial backing and transportation, and Tommy's cousins sometimes help out, but they're at ballet today."

Tommy started giving puppet shows at family reunions when he was four. When he was eight, one of his cousins had a birthday party with a professional puppeteer.

"He charged them about $80," said Tommy. "The next year I did it and I didn't charge them anything."

Ever since, Tommy has been entertaining -- usually for a fee -- at birthday parties all over the District and Maryland, at school and church functions and, last fall, on the NBC show "Stuff."

"I used to reprimand him when he cut up his socks to make puppets," recalled Jean Duren. "Now I permit him to cut up his socks."

Tommy makes the puppets and the sets in a studio in the basement of the Durens' home in the Michigan Park section of Northeast Washington. The basement also houses Tommy's science laboratory. n

"I'm a professional puppeteer," said Tommy, in answer to the inevitable question. "But when I grow up I want to be a zologist and save animals from extinction. This is for my college money."

Tommy peeks through a window in the set and sees the several dozen children and adults are ready for the show. His grandmother and grandfather join the audience, but his mother stays backstage to help with lights and music.

Half an hour later, we've shifted from the 24th century back to the 19th and finally to the 20th, and the kids come backstage to get Tommy's autograph and touch the puppets. Someone asks Tommy how he gets the ideas for his shows.

"Well, I read a lot," he replies. "And sometimes I get an idea in a dream. If I have an idea I write it down first thing in the morning."

The little kids want to play with the puppets, but Tommy has to keep them in shape for the next show. Instead, he lets them feed the puppets little discs of cotton. A puppet bites one little boy, but Tommy reaches into the puppet's mouth and extricates the kid's finger.

"Puppetry is a good way to express your feelings," says Tommy as the kids file out. "If you don't want to show your face and express your feelings, you can let the puppets do it for you."