Manny Garrido, 23, of Lake Worth, told investigators he began tinkering as a way to pass the time after his driver's license was suspended and one of his projects was a single-round, .40-caliber gun he constructed from a brass tube, a large nut, springs and a screwdriver, the South Florida Sun Sentinel reported Tuesday.
Garrido accidentally shot himself in the leg with the gun while it was in his pocket March 29.
Detectives later discovered Garrido had pleaded guilty to felony drug charges in April 2011. It is illegal for a felon to possess a firearm or ammunition in the state of Florida.
Garrido remained the Palm Beach County Jail Monday in lieu of $7,500 bond.
Garrido's father, Manny Pinho, said he does not believe his son did anything wrong.
"Who hasn't tried to building a sling shot or bow and arrow in their lives?" Pinho said. "It was an experiment that went wrong."