Visitors to the 21st Fourth of July weekend Berkshires Arts Festival at Ski Butternut in Great Barrington, Mass. July 1,2,3 may wonder if they are at times fooled by what they see. They'll be looking at basketry when it's pottery; a painting when it's needle felting; a zipper on a wood vessel not of fabric and metal but also of wood; a photograph that's actually ceramic and what appears to be a ceramic sculpture, an intricate work that's actually of wood.

These exhibitors achieve their own kind of optical illusion. They do so in different ways:

• Some of Paul Petrie's sculptures are so delicate they look like ceramic yet they are wood.
• A zipper appears to open a wood vessel by Chris Wakefield but it isn't metal and fabric, it, too, is wood.
• Is it paint? Watercolor? No--it's a picture in needle felting by Juliana Boyd.
• Rick Epstein's landscapes look like photography on paper and yet the images are on ceramic.
• Lynne Puhalla, potter, weaves clay-based baskets with dyed reeds and other fibers to achieve the look of a basket filled with mystery.

The work of these artists joins 150 other exhibitors. In addition visitors to the Festival will enjoy live music, craft demos, workshops, entertainment and kid's activities. The family-oriented festival is produced and curated by An American Craftsman Galleries, Lenox, Mass. It will include artisans who design and create jewelry, ceramics, photography, sculpture, art glass, furniture, painting, fashion and works in wood, metal, mixed media, leather and fiber.

Friday and Saturday July 1 and 2, 10:00 a.m to 6:00 p.m. Sunday July 3, 10:00 a.m. to 5:00 p.m.

Adults $14; Students $7; Weekend pass $16; Children under 10, free. No pets unless service dogs.

Ski Butternut, Rte 23, 380 State Road, Great Barrington, MA 01230