There are three harmoniums, six African thumb pianos, one Brazilian berimbau, a Chinese gong, five sets of wooden bones, 50 penny whistles and three Middle Eastern drums hanging from the walls of David Eisner's House of Musical Traditions in Takoma Park. But it was only after people asked for them that Eisner began stocking guitar strings.

"We began by specializing in ethnic and esoteric instruments," recalls Eisner, who opened his shop, a cornucopia of records, books and folk instruments from around the world, in 1972. "We expanded from nonwestern instruments to folk instruments -- and became the local music store."

On a recent Saturday afternoon three bluegrass musicians jammed near the front of the long, narrow shop, the soft sounds of a dulcimer echoing off the pressed tin ceiling as customers browsed through the blues, klezmer and folk albums. Eisner's shop offers music lessons and special workshops from visiting and local musicians, often held in converted studio space atop the store at 7040 Carroll Ave. Local musicians stop by to check out the latest instruments that Eisner has bought on consignment or picked up at auctions -- like a rare Hardanger fiddle from Scandinavia, its fretboard inlaid with bone and ivory and its scroll carved with gargoyles. And there's always a berimbau -- a strange rhythmic instrument with a long metal bow, resonating gourd, and woven basket shaker -- in stock.

But 15 to 25 percent of the business, according to one of Eisner's assistants, is from mail-order sales, and it's not uncommon for someone from Texas to call up inquiring about the latest Appalachian concertina. Says Bill Jenkins, an accomplished bass player and manager of the shop, "David's secret has been to develop a cadre of instrument makers from around the world. It's what's taken him 10 years to develop."

The craftsmen include an African man, now living in Washington, who makes the Botswana thumb pianos and talking drums, a group from Sri Lanka that makes snake charmer flutes, and an American group that builds traditional Arabian dumbeks, hourglass-shaped drums whose goatskin heads sound a resonant doom and whose ceramic or metal rims give a sharp bek. Bart Lustig of West Virginia makes Bart's bones, curved pieces of wood or bone that are played like spoons.

"Bones are the basis for Irish jigs and reels, and were also used in traveling minstrel shows," Eisner explains. "We had a lady who used to make them for us out of animal bone, but it became too hard for her to get good cow shinbones from the butcher."

And then there's Swedish-born craftsman Tomas Ohrstrom. Now living in Takoma Park, he's been making wooden flutes and goatskin drums for Eisner since 1977, and also helps out in the store. Ohrstrom builds the large Japanese shakuhachi flutes from the root end of bamboo ("it's sophisticated -- there's a great latitude of pitch and volume in the low tone," he says), as well as crafting South American notched flutes and standard transverse flutes.

According to Eisner, an easygoing sort in his mid-thirties, partial to Hawaiian shirts, his foray into musical exotica began in 1970. As a student at the University of Maryland, he was organizing a concert series on the chapel lawn when he first heard the strains of a sitar and dulcimer. "I asked my friend, 'Where did you get these great instruments?' " Eisner recalls. He traced them to a New York City store called the House of Musical Traditions, and the following year divided his time between training at the New York store and studying at the university.

When the couple who owned the New York shop decided to build dulcimers full time, Eisner bought out the remaining stock -- about $1,500 worth of nonwestern instruments -- and moved it to Takoma Park. "People bought everything," he says. "They even asked us for guitar strings."

In 1974 the New York-born Eisner decided he wanted to learn about country life and settled on a farm in Berkeley Springs, W. Va. He moved his music shop there the following year, transplanting it in a Victorian house on Main Street. "It was a great experience for someone who knew only the wilds of New York City," Eisner says. He formed an arts council at the request of the county, began the annual Apple Butter Festival, a fall folk concert series that still thrives, and started a monthly folk dancing program. "I ran the first sitar-flute-tabla bluegrass concert in Morgan County," he says.

Eisner returned to Takoma Park in 1981, when his old Carroll Avenue shop space became available. A concert series he began in the shop soon expanded to the Takoma Cafe across the street, and the hundreds of albums stocked became thousands. Through the Washington Folklore Society and musicians frequenting his shop, Eisner developed a staff of musicians and craftsmen to help run his store.

Says Jenkins, "Last year was our biggest year ever. We're experiencing growing pains -- like counting money . . . A folk store is supposed to go out of business, that's the politically correct thing to do. We're supposed to be a hangout, a social phenomenon. We want that, but we want to see if we can be a business, too -- that's the challenge."