Who makes activist/political arts? The individuals and groups who make this kind of cultural production are primarily: movement actors [e.g. activists] within the communities meant to experience and co-create the work; artists, cultural activists, tool-having professionals, also often from within the discourse communities. These groups are far from mutually exclusive and often involve a lot of cross-over.
People in Social or Political Movements [activists, radicals, insurgents]
Folks from within activist or movement communities self-produce within a community/ies for multiple purposes. Social Movement Actors is a term used by social movement scholars to talk about the people involved in social movements. This term implies participation as well as self-identification with the social movement. One can not accidentally be a social movement actor, unlike in participatory art, where one can walk into an art piece unawares and end up participating.
Types of work made include: banners/puppets for protests [Beehive collective, everyone who’s ever made a sign on cardboard], political poetry [like by Voltarine de Cleyre, June Jordan or Marilyn Buck], political publications and communications [made by radical print and design workers]. There is a “bread and roses†element at work here: an urge to make beautiful things for instrumental purposes.
Social movements also use the concept of repertorie for this kind of production, claiming that actors pick forms of protest strategically from an existing set of possible actions, based on opportunity, access, desired impact et al., in relationship to desired outcomes from the state response.
Artists
Movement players are often also artists or cultural workers, and the venn diagrams of these identities works within political collectives: many have artists in them incidentally, others are for artists specifically. And some artists are specifically political or socially engaged without being part of a specific organization, they still make work that reinforces political or movement claims.  There is a long history of art that is made with a social and political intention that closely matches the activist cultural productions made within social movements – and often there is intentional overlap. Professional and non-professional artists and cultural workers are found equally in this group.
Group Crossovers
There are plenty of examples of activists who were artists, and users who were creators. The 1980s and 1990s produced many political arts collectives [see Alan Moore’s Art Gangs for a wonderful first-person description] and examples like Gran Fury, ACT-UP, and WAC all have gotten a fair amount of historical research.
Women’s Action Coalition (WAC) was an open alliance formed by a group of artists and friends in New York City on January 28, 1992, in response to the outrage they felt about Supreme Court Justice Clarence Thomas’ confirmation hearings. This group was committed to direct action and made up of [mostly white, professional] women artists who used creative cultural works to respond to sexism in the world, which turn into responding to sexism in the art world. Much more on and by WAC here: http://www.uic.edu/depts/lib/specialcoll/services/rjd/findingaids/WAC-Chicagof.html
Restrictions on Makers in the Art World
Since political art is contentious and does not necessarily “count†as art, it’s not always in an artists’ best economic [read: professionalizing] interests to create it, since it can indicate a lack of commitment to institutional or market concerns. However, professionally-trained artists continue to have social and political concerns which they use their art training to address.
Likewise, amateur or “outsider†artists may have less access to sites of display of the art or tools for creation, but are less restricted by concerns of being delegitimized by their peers or critics.
Readings:
Art Gangs: Protest and Counterculture in New York City, Alan W. Moore, 2012. http://www.artgangsbook.com/
Contentious Performances, Charles Tilly, 1998.
Dynamics of Contention. McAdam, Doug, Sidney Tarrow, and Charles Tilly. Cambridge: Cambridge Usniversity Press, 2001.