The NYPD convened Tuesday what the commissioner called a “show and tell” of bullet-resistant glass and doors to be installed on more than 3,800 patrol vehicles.

The bullet-resistant doors will be installed by the end of the year; the windows by the first half of next year, said Mayor Bill de Blasio.

“You saw that material, very high tech material, that absorbs the bullet and literally takes the bullet’s trajectory and uses it against it to stop it dead in its tracks,” de Blasio said inside a classroom the NYPD uses to train cops.

Police Commissioner James O’Neill said the need to protect cops in vehicles from gunfire was motivated by the 2014 shooting deaths of Rafael Ramos, 40, and Wenjian Liu, 32 — officers who were ambushed by a mentally ill gunman as they sat in a patrol car in Brooklyn — and the killing the following year of Brian Moore, 25, a cop who was shot by a suspect in Queens.

Money for the remodeled training facility and the bullet-resistant windows for every NYPD patrol vehicle is in de Blasio’s draft $84.7 billion budget for the upcoming fiscal year: $10.4 million for the windows and $275 million for the remodeling.

The plan also will modernize Rodman’s Neck, which the NYPD took over in 1960. Among other changes, the department will seek to muffle gunfire that rattles neighbors on nearby City Island.

Councilman James Vacca (D-Bronx) says the noise has long been a source of consternation among his constituents.

O’Neill said construction of the facility is long overdue.

“I think the same dining hall’s been up here forever. I think I remember eating meatball sandwiches back here way back in 1983,” he said. “It might even be the same meatballs.”