Participants reciting "The Blessing of the Bees," a poem written by Jesús del Toro for Pedro Reyes's exhibition "pUN." Courtesy Queens Museum of Art, New York. Photo Ramiro Chavez.

Participants become the protagonists in Pedro Reyes's at once playful and serious art productions, which have grown ever more complex over time. The 42-year-old Mexican artist, who considers himself primarily a sculptor, creates flexible objects that can communicate both when statically displayed and when activated as props in his performances and events. In his most elaborate undertaking to date, Reyes choreographed a kind of political cabaret called "The People's United Nations," or "pUN," which unfolded over the course of a weekend last November at the Queens Museum in New York. All the sculptures, signage and wall pieces he designed for "pUN" remained on view at the museum through March 30.

Tapping into the personal networks of the museum's staff members, Reyes gathered volunteers representing 160 nations as civilian delegates for this unconventional summit, where they used games, group therapy techniques and theater exercises to tackle global issues—including climate change, food security, war, drugs and immigration—that might otherwise seem overwhelming to nonexperts. Following a step-by-step activity book prepared by Reyes, small groups of delegates were asked, for instance, to present each other with problems affecting their countries and solicit the most wildly optimistic solutions—turning a negative into a positive, or, as the artist calls it, "flipping the tortilla." Each group then crafted their favorite proposals into catchy headlines and shared them with the entire assembly. "Israelis Marry Palestinians, Have Beautiful Children" drew the most thunderous applause and laughter. The convention took place during regular museum hours, and tour guides led the public around the periphery, just as tours are conducted in the actual United Nations. 

Presiding over the Queens Museum atrium was a huge sky-blue flag emblazoned with the "pUN" logo—an open hand with an eye in the palm superimposed over a globe—which Reyes designed to symbolize world protection. The logo was also painted on wooden boxes that were used as platforms, tables and podiums during the conference and then lay scattered casually around the space for museum visitors to sit on. Reyes's sleek icons and wall graphics nodded to the stylized signage that was developed for the 1968 Summer Olympics in Mexico City and that still graces the subway system there. One of the show's acrylic wall icons represented the grasshopper burger that Reyes served to delegates for lunch, offering it as a small-carbon-footprint food of the future. A luminous white fiberglass sculpture hung overhead merges a military drone with a dove. "It transforms an agent of death into an agent of life," Reyes said during an interview at the museum.

A large floor piece composed of interlocking, organically shaped pieces of white marble evokes sculpture by Isamu Noguchi but is in fact an assortment of cartoon-style speech bubbles. Intended as a representation of the different voices and emotions involved in "pUN," it perfectly mirrored an unscripted incident that occurred during the performance weekend. On a tightly scheduled afternoon, the Portuguese delegate announced that he was tired of hearing only English and wanted to open the floor to the various languages of the participants. Members erupted in a polyphony of greetings and sayings in their native tongues that lasted half an hour. It was a small revolution of positivity that had Reyes beaming from the sidelines.

Born in Mexico City, where he still lives, Reyes trained as an architect at the Ibero-American University and comes to his projects with an optimistic design approach, imagining hopeful solutions to personal and social problems. Even as a child, he drafted schemes for utopian cities, which his parents—both chemical engineers—would critique in terms of how well they were drawn. In the mid-1990s, after completing his studies, Reyes opened an exhibition space in Mexico City, in an abandoned tower built for the Olympics. His plan was to exhibit experimental architecture, but, finding architects too conservative, he decided to show work by artists instead and, for a time, used the space as his own studio. One of his earliest design concepts was the Capula, which he has adapted in several projects since 2002. Challenging the idea of rigid, right-angled rooms, these large capsulelike forms—made of stainless steel and elastic vinyl string and suspended midair—invite people to climb inside, where they experience the feeling of being in a gently swaying cocoon.

Among Reyes's first participatory sculptures was Collective Hat (2004), which consists of more than two dozen sombreros stiched together. Resting on the floor, the work could read as a stylized mountain range or a cellular structure as well as, humorously, just what it is. The artist took this multiheaded organism to plazas in Mexico City and convinced strangers to come together and wear it. The work became a study in democracy and absurdity, as the crowd had to negotiate how to move as one. Reyes's approach to providing tools and designing systems for interaction can be viewed in the context of other contemporaries working with social practice, from Rirkrit Tiravanija to Oliver Herring to Tino Sehgal. Yet Reyes is personally more influenced by the histories of theater and politics than the lineage of performance. He freely acknowledges the specific genealogy of his projects and feels ideas aren't useful if they can't be copied.

Seminal to Reyes's development is the Brazilian theater director and politician Augusto Boal, whom he met in 2007, shortly before Boal died. In the early 1970s, Boal founded the Theatre of the Oppressed, which enables spectators to step into the place of the actors and steer a play to alternate conclusions. This technique has been implemented worldwide for social and educational purposes, including in Rio de Janeiro in the 1990s when Boal, elected city councilor, used it in policy-making by replacing legislators with ordinary citizens. This idea of de-professionalization underpins Reyes's use of performance, particularly in "pUN," where he invested regular people with the authority and responsibility to make decisions about improving the world.

Another South American visionary who's become a mentor and friend to Reyes is Antanas Mockus, the mayor of Bogotá in the late 1990s and early 2000s. Mockus turned his city into a kind of nonstop performance with humorous initiatives to shift public behavior, such as hiring mimes to make fun of traffic violators. At the Creative Time Summit in New York last October—which explored art, place and dislocation in the 21st centry—Reyes and Mockus discussed onstage how Mockus won the 1995 election on a platform that included a pledge to impose a voluntary 10 percent tax increase. The incentive was that people could choose where their money would go. They were given a chip at the tax office to use at a makeshift casino with Plexiglas tubes showing all the projects that needed funding. Sixty-three thousand people paid to play. Inspired by the idea that people would choose generosity over greed if given decision-making power, Reyes created an exercise for "pUN" called Defense Budget Reallocation. Delegates were given chips representing the defense budgets of their nations and a choice of security projects promoting peace over war—such as helping people who had lost their homes in environmental disasters—to which they could redistribute the symbolic funds.

Mockus was also a catalyst for a string of projects in which Reyes repurposed guns into life-affirming objects. As mayor, Mockus organized a day for people to swap their guns for food stamps within the privacy of confessional booths. In 2008, inspired by Mockus, Reyes carried out a similar project in Culiacán, Mexico, a city with a high rate of gun violence. He created television ads inviting citizens to trade their guns for coupons to buy useful appliances. Then he melted down the 1,527 firearms collected and recast the metal into 1,527 shovels to plant trees in Culiacán's Jardín Botánico. Through the program, called Palas por Pistolas (Shovels for Guns), shovels have been distributed to schools and art institutions in over 20 cities worldwide, providing opportunities for people to come together and nurture new life with material once used to end life. 

In 2012, Mexican government officials, aware of Palas por Pistolas, contacted Reyes to see if he would be interested in the metal parts from 6,700 guns that had been confiscated and dismantled. Wanting to make sculptures that would bring people together as the shovels had, Reyes decided to create musical instruments. He collaborated with a group of musicians to make the assemblage-style devices, choosing components by shape or sound potential and then welding them together. These percussion, string and wind pieces, composing a series called "Imagine," produce harsh yet hauntingly beautiful sound. They were first played in a concert at the Mexico City gallery Proyecto Liquido in 2012, and traveled that same year to the Gwangju Biennial, the Istanbul Design Biennial and London's Lisson Gallery, which represents Reyes. Reyes spoke of the music made from the neutralized weapons as both an exorcism and an elegy.

The following year, Reyes worked with software engineers to produce "Disarm," a second series of gun-part instruments, this time operated by computer. Seven of them, including a wind chime, a stand-up bass, a xylophone and a drum set, were on view in the Carnegie International in Pittsburgh this spring, creating a continuous sound environment in the Carnegie Museum of Art's grand Neo-Classical marble hall. These automatons look shocking—kind of Mad Max meets Tinguely—but produce angelic music. The instruments each got a solo turn and periodically, including for a slinky Pink Panther-esque arrangement, came together in symphony. Tina Kukielski, one of the three curators of the International, reported that large crowds of visitors often burst into applause when the instruments played in unison, something she had never witnessed before for an artwork without a live performer.

Instruments from "Disarm" were also shown earlier this year at the University of South Florida Contemporary Art Museum in Tampa as part of the group exhibition "CAM@25: Social Engagement." In January, Reyes led a workshop there called "Amendment to the Amendment/(under)stand your ground." He worked with students from the university, located just a few blocks from where Trayvon Martin was shot, to rewrite gun laws using Theatre of the Oppressed techniques. Consistent with Reyes's system-based approach to all his work, these gun-transforming projects build on one another and ultimately aren't dependent on the presence of the artist to activate a community.

Another project that has had multiple iterations is "Sanatorium," a temporary clinic that Reyes designed. Providing up to 16 therapies blending art and psychology, the clinic is intended to treat problems like loneliness, anger, malaise and stress. Similar to "pUN," it's a playhouse of choreographed interactions for groups of participants, but the emphasis is on personal rather than global issues. The project started as a commission by New York's Guggenheim Museum in 2011, when Reyes set up the clinic in a storefront in Brooklyn. In two-hour sessions, people engaged with volunteer "therapists" who had been trained by Reyes. Subsequent versions were done at Documenta 13 in Kassel, Germany, in 2012 and at Whitechapel Gallery in London in 2013. In June, "Sanatorium" will open at The Power Plant in Toronto, where volunteers will implement his Operations Manual, which for each therapy gives detailed instructions, describes the theoretical underpinnings and provides testimonies from previous volunteer therapists.                  

Participants in one of the clinics might be asked, for instance, to write down a secret anonymously, put the paper in a sealed bottle and deposit the bottle in a tub of water. Then they can choose another bottle and read someone else's secret. Thus, according to the artist, they are able to experience both the catharsis of confession and a pleasure similar to that of gossip. At another station, participants might draw the faces of the people who hurt them most on balloons affixed to dummies. Therapists will then encourage them to vent their rage verbally and physically, and afterward will administer sugar pills as a "vaccine" against real acts of violence.

The most complete aesthetic and psychoanalytic experience offered in "Sanatorium" is a therapy called the Museum of Hypothetical Lifetimes. Reyes designed a white architectural model of a hypothetical museum interior with appealing curves and zigzags. The galleries each represent a particular aspect of life, with labels including "Mother," "Classroom," "Career" and "Aging." Participants can choose from a large assortment of objects and figurines and install exhibitions of their own life stories—present, past and future—in the architectural model. In doing so, they produce physical maps of their inner worlds, something children do unconsciously—when playing with building blocks, for example—and artists keep doing professionally but most people give up as adults.

In most every project, Reyes offers a combination of beautifully designed objects, opportunities for fun and games and a multilayered lesson. There is a lot of text-wall labels, handouts, scripts—in which he co-opts and marries ideas from figures such as Karl Marx and Adam Smith, Che Guevara and Ben & Jerry's cofounder Ben Cohen. Reyes is committed to the idea that art can change minds and promote peace. His revolution is spelled out. If the work is didactic, it's always double-sided.

Take Leverage (2006), a seesaw structure that balances a single person on one side with nine people on the other, requiring participants to form a group in order to play. The piece can be seen as a metaphor for the asymmetry within social organizations in which the power is wielded by the economic elite, a boss or a dictator. Yet flip the tortilla and the piece could encapsulate Reyes's whole buoyant artistic enterprise, where the vision of an individual has the power to move the entire group.

OPENING SOON "Sanitorium," an installation and performance project, at the Power Plant, Toronto, June 28-Sept. 1.

HILARIE M. SHEETS is a New York-based art writer.