Squeezing their shapers, two children circled each other as intently as lightsaber duelists in "Star Wars."

The shaper is one of the new musical instruments that MIT composer Tod Machover and his team have developed for their music education and performance project, "Toy Symphony." It enables a young player to achieve subtle effects of color and dynamics that it would take years of study to master on a traditional instrument. The young player is instantly in charge; by the way he squeezes the shaper he creates the sound he wants. The duelists on a recent afternoon in the Children's Museum weren't doing anything dangerous; they were improvising a duet.

Down the hall another workshop was going on for six budding beatbug virtuosi, ages 8 to 11. The beatbug is a new plastic percussion instrument that looks like a friendly insect. Composer Gili Weinberg was seated in front of the semicircle; each child had his or her own assigned rhythm, but the group learned them all, first by clapping. Then each started tapping his or her own rhythm onto the beatbugs, which fed them into the computer; the superimposed rhythms were adding up to something new and exciting.

The Fisher-Price toy company will be introducing shapers and beatbugs to the commercial market. Fisher-Price will also be using the third musical "toy," a computer program called Hyperscore. By drawing lines of different colors on the screen and creating patterns for them, a child, or an adult, can compose music without needing to learn how to read it or studying harmony, counterpoint, theory, and compositional technique. You can check it out yourself by downloading a free version of the program from the "Toy Symphony" website, www.toysym phony.net.

At a Hyperscore workshop at MIT on a very rainy afternoon, another group of children, drawn from earlier groups at the Boys and Girls Clubs of Boston, worked on putting the finishing touches on their own compositions.

To one of them, Machover was describing classical sonata form. "It's like taking a trip; you are at home, you go away from home, and then you come back home, and you've changed." To another, he said, "This is very, very fast, faster than instrumentalists could play - they'd have a heart attack. This is your challenge: to see if you can slow it down without losing any of the excitement."

At the end there's a recital, and the composers talk about the names of their pieces.

Teyanna Powell-Hughes, 10, of Dorchester, has produced some complex and dramatic counterpoint, but she doesn't know what to call her piece - she's thinking about "The Tunnel." Leonardo Tannenbaum-Diaz, 11, of Arlington, has written a scary, jagged piece, "Times Change." "It sounds like `Jaws'! " someone exclaims.

Ben Tucker, 11, from Hingham, continues the John Williams motif with his ingenious perpetual motion piece. "I call this `Far away in a galaxy, long, long ago . . ."

Then it was time to come back to earth for some cake.