An East Harlem man blasted himself in the chest with a nail while trying to build a “zip gun” in his bathroom on Saturday night, police sources said.

The 46-year-old was inside 347 East 118th St. when he accidentally shot himself around 7 p.m., the sources said.

The man told police he took a slug, but a Harlem Hospital doctor determined he was wounded by a nail.

The man was admitted to the psychiatric ward, cops said. Components for making the fake gun were found inside the apartment, police sources said.