Nestled between the big department stores and the endless shoe/dress/record/jewelry marts of downtown are some obscure specialty shops that make the area a maketing adventure.

A real find tucked behind the Martin Luther King Library is Keene's Model Railroad Shop (907 G Place NW), which deals exclusively in HO-gauge train products. In a room lined with old prints of locomotives from Pennsylvania Railroad calendars, you can find everything you need to repair an old set, make your own or start a brand-new one. Keene estimates that most of his customers are adults who, like himself, have never lost the thrill of a choo-choo.

A real trick is to whisk yourself up to Al's Magic Shop (1205 Pennsylvania NW), where on any given day local prestidigitators are likely to be hanging around comparing notes.

A newcomer to downtown is Kendall's (802 H Street NW), which features new and used comic books and related art. Around the corner is Jenks Hardware (738 7th Street NW), which artist friends say has the best selection of handcraft tools in the city. Up the street is a new branch of the General Store (810 7th Street NW), with bargain-priced jeans, sweaters, leatords and Lord knows what else. Nearby is Wang's (800 7th Street NW), an Oriental department store with the best deal in town on kung fu slippers.

One of the more mysterious stores - nobody seems to know its business hours, for example - is Jack Mullane's Costume Rentals (718 11th Street NW). Even if it's closed, which it usually is, the masks and costumes in the window make for good browsing.