(CNN) - With the glide of a paint roller, Manuel Oliver silently released a loud call to action -- "We demand a change."
His son Joaquin "Guac" Oliver was one of the 17 victims slain in the Marjory Stoneman Douglas shooting. Like Joaquin's classmates, Oliver is determined to make sure no more families suffer the same tragedy.
"He didn't say anything, he was just breathing heavily while painting. He was very focused," Lex Michael, a Parkland survivor who captured the emotional moment, told CNN. "It's not shown in the video but Oliver also took a hammer and created holes in the wall and put flowers in them."
The father then invited students to sign their names and write notes of support on the mural.
The event is part of "Parkland 17," an art exhibit organized by Miami Heat player Dwyane Wade and created by artist Evan Pestaina in Wynwood, Miami. It also includes empty desks with students' names and a phone booth where visitors can "Call Your Rep" to talk about gun control, according to Michael.
Oliver put the artistic platform to good use, and it's not the only way he's advocating on his son's behalf.
Last week, he and his wife founded Change the Ref, a nonprofit organization empowering young activists with the tools they need to make their voices heard.
"They are not the light after the tunnel," Oliver says in a video on the organization's website. "They are the light that is lighting the tunnel right now."
Change the Ref will enlist professional athletes to encourage younger generations in their pursuit of a "fair game in Congress," according to the site. The organization also aims to fund a "Youth Think Tank" to help young people develop their leadership skills.
Next fall, they plan to host a youth forum in honor of Joaquin, as well as a "Put Yourself in Your Kids Shoes'" tour to get parents involved.