Here are some of the warning signs next to the artwork: "Viewer Operated Sculpture, Caution Moving Parts" and "Please do not touch works on display and observe care while walking through this exhibition. Parents are advised to supervise children carefully."

The work that carried the first warning was Vito Acconci's "Fan City." The second was Alice Aycock's "Hoodo (Laura)." Both are part of the Hirshhorn's new exhibit, "Metaphor: New Projects by Contemporary Sculptors," and about 600 people attended the exhibition's opening last night.

Lots of arching steel, whirring parts, and expanses of machinery. Or as Sidney Lawrence, Hirshhorn staffer, put it: "Either you participate or something moves."

A work by Lauren Ewing is called "Auto-Plastique: The Prison." It is a prison-type structure and across from it is a sort of phonebook without the phone -- a corner structure with a seat and a horn to speak into ("The Perfect Speaker").

"I get asked a lot of things," said Ewing, clutching half a dozen red roses and one black silk rose, all gifts. "People ask what is the prison? Why the prison? My answer is that in the last year I've built six institutions. When I want to take a look at something, I build it. I make one!" She laughed, wide-eyed. Her works include a bank, a library, an asylum. "I'm currently trying to get a commission to do a school," she said.

Reaction varied. Joan Mondale: "I'm very excited. It's wonderful. Allen, we have to find Aaron for the tour," she said, organizing friends who came with her into a group. "It's very new, it hasn't been seen before. But as Alice and I were discussing, art opens your eyes. It helps you see the world in a new light."

Said Walter Schwartz, a gallery visitor standing behind one mammoth curve of steel, a piece of "Hoodo" referred to as "a ghost catcher net" in the Aycock exhibit: "It's strange, let's put it that way."

From local artist Robin Rose: "It costs a lot of money to build these things. These artists are serious. Part of what they do is to try to convince people how serious they are about it."

From one friend of Tracy Wall, the engineer who worked on the whirring fans and the rocking orb of Dennis Oppenheim's piece: "Any place we can see this take off?"

Oppenheim's "Launching Station #1 and Armature for Projection," was a turbulent mix of motion and noise. "I was stunned by your work," said one admirer. "Thanks. We're going broke," replied Oppenheim, with a chuckle.

Someone else told Oppenheim that they just returned from browsing through his exhibit. "You survive?" asked a grinning Oppenheim. "You walked through there without getting your heels clipped?"

Oppenheim says his work represents "lots of power." But he says he's going broke because "these things are so expensive to do."

Can't sell them?

"You can't give them away," he said. "We've tried." He takes a sip of his beer. "I never thought I'd be building things that I couldn't even give away."