Luis Bedoya is baby-faced and skinny.
And he looks ever the boy when he puts on an industrial-sized apron, thick gloves and a metal helmet - the tools of an apprentice welder at the Don Bosco center in this city in southern Colombia.
It's a big complex, complete with classrooms, basketball courts, a dormitory and work rooms. It's home to boys and girls, as well as very young adults, who defected from the FARC rebels or were captured by the Colombian army.
The training is preparing Bedoya for another life, one far different from the one he had in Colombia 's remote jungles.
Bedoya spent four years in rebel units that had large contingents of teenage fighters, trudging over mountains before dawn and fighting army troops.
It was always hard, says Bedoya, who's now 20.
You never knew when you were going to be shot, or when a bomb was going to fall from above.
Captured by the army, he was sent here to Don Bosco, one of several centers set up to serve former child guerrillas.
It's a place where on a typical day, dozens of children happily run around in a big patio, while others play ping pong and listen to music.
Most of the former rebels are in some kind of vocational training - like learning to work on car engines.
About 500 children are in programs like this across the country, but if peace is achieved, experts anticipate a much greater need.
"I think the number of children that are in illegal groups like the FARC is under-reported and I do think that the FARC has traditionally depended on the use of youth ... to be the front line of the work that they do," says Provash Budden, who heads the Colombia office of Mercy Corp, a U.S.-based group that helps run Don Bosco.
The FARC, which has been fighting to take power for half a century, is now in peace talks with the state. On Sunday, the two sides announced a major breakthrough on a complex issue, land reform.
Still, as the two sides talk, the FARC has been stepping up its recruitment of child fighters. Indeed, thousands of children may have become rebels in recent years, even as the FARC lost ground to Colombia's army, which is backed by the U.S.
"Although that the FARC is now engaged in a peace process with the Colombian government, there are trends that indicate that there is an increase in recruitment, especially in the rural areas of Colombia where government institutions don't have as much reach or influence," says Budden.
No one, though, knows exactly how many children are in the FARC, but Mercy Corps says it could be thousands.
"It's a crime and it shouldn't be done. The place for children is school, the place for children is the park, and it's not combating in any guerrilla group," says Alma Perez heads a government office that tries to prevent the recruitment of children.
At Don Bosco, the former rebels give all kinds of reasons for why they joined a revolution – from boys who liked the guns to girls who wanted to join their friends.
Jasmin Fandino, who's now 20, says she joined because of abuse in her own family. In the FARC, she survived air force bombings and army strikes.
"It was very hard for us," she says, speaking of when her friends were killed. "You began to feel alone."
These days, Fandino is far removed from that life. She's in cooking classes, and looking forward to higher studies - and maybe some day opening her own restaurant.