Forget the chores and tank up the car. "Open Studio '85" begins today, the once-a-year, two-weekend-long opportunity to peek over the shoulders and into the studios of some of the best -- and some of the newest -- artists in town.

This year more than 300 painters, sculptors, photographers, printmakers and mixed-media artists and craftsmen have banded together to lure visitors into their assorted working quarters with the hope of stimulating both interest and sales. The Washington Project for the Arts-sponsored event -- which started with a mere 15 studios seven years ago -- is now an unjuried free-for-all, open to any artist working inside the Beltway and some groups outside. It has now grown so large that it encompasses four days, divided by location: Virginia studios will be open today from 11 a.m. to 6 p.m., Maryland studios tomorrow. Next weekend, the District will be featured -- downtown artists on Saturday and uptown artists on Sunday.

Lists of participating artists, with directions (occasionally incorrect) to their studios are available, free, at the Arlington Arts Center, 3550 Wilson Blvd., Arlington; Armory Place, 925 Wayne Ave., Silver Spring; Herb's Restaurant, 2121 P St. NW and WPA Bookworks, 400 Seventh St. NW. Anyone unsure about where to begin the tour would do well to head straight for the Spring Hill Site Project in McLean, one of the most adventurous sculpture shows to turn up in Washington in some time.

Brought to life by sculptor Emilie (Muska) Benes Brzezinski (following a suggestion by Corcoran curator John Beardsley), the show includes some 20 site-related works by nine hitherto unrelated sculptors who joined together for this event: Leonard Cave, Steven Cushner, Walter Kravitz, Timothy Makepeace, John McCarty, Jerome Meadows, Judy Miller, Jeff Spaulding and Brzezinski herself. The result: the rolling lawns and groves of trees surrounding the Brzezinski home at 1061 Spring Hill Rd. in McLean have been temporarily transformed into a very special sculpture garden.

Sculpture has always been related, one way or another, to its site. But in current parlance, "site sculpture" means work that relates to -- and somehow transforms -- a specific site, and cannot be separated from it. That is surely true of a two-part piece made from wood and bronze by John McCarty, set in a small clearing near a chicken coop -- an evocation of a primeval offering place, or the "sacred ground" the artist had seen in a monastery in Tuscany. There is also a handsome but more traditional crushed steel sculpture by McCarty, sensuously twisted and curved, and richly patinaed to echo the russet leaves of a nearby dogwood. But this piece, like most others here, has more to do with being well-placed than with being site-specific.

Leonard Cave has done a bit of both in his sprawling, expansive piece titled "Desert Story," built on the site from timbers bolted to hacked chunks of wood and bleached maple burls, all set on a bed of red stones found nearby, once part of a dismantled wall. Jeff Spaulding's beautifully crafted wooden sculptures, shaped like giant scythes, blend perfectly with the landscape; Jerome Meadows' long-legged anthropomorphic shapes, made from laminated wood, look like off-duty sentinels guarding the house.

But it is Brzezinski herself whose work makes the most dramatic and unforgettable statement here. Best-known for her clear, cast-resin sculptures of tree trunks, shown at Osuna Gallery and elsewhere, Brzezinski has long sought a way to show the giant latex molds from which she took the original impressions of the trees -- huge, extraordinary-looking blankets of latex that had picked up not only the surface textures, scars and graffiti of tree trunks, but their inimitable colors as well.

The sight of these rubber molds slung over the rafters of her garage inspired the "Relic Tree" that stands at the top of the circular driveway -- a towering beech from which hang several molds that look much like drying hides, vestiges of past life. But it is her "Druid Stage" that steals this show -- several heavy curtains of latex -- some 13 feet tall -- tumbling heavily into folds, but -- despite their weight -- seeming to grow out of the ground. Together, they make a magical forest in a grove of real beech, maple and locust trees that would make a perfect setting for the dance.

Amazingly, this show was organized after only two meetings -- one in which each artist chose a site, and another at which the works were installed. There was no budget, "but a lot of faith," says Brzezinski.

The Spring Hill Site Project will be open today and every day through Sept. 29 from noon to 5 p.m. The directions on the WPA map are wrong. To get there, take the Georgetown Pike (exit 13 west from the Beltway) away from Washington. At the bottom of the hill, turn left onto Swinks Mill Road. At the light, turn right onto Old Dominion Drive. At the 7 -- Eleven, turn left on Spring Hill Road. The third driveway on the left is 1061 Spring Hill Rd.