A Manhattan photographer was the first person to find the second explosive device in Chelsea on Saturday night — and almost didn’t report the contraption to cops because she thought it was a kiddie science project, she told The Post on Sunday.

“I had just taken maybe 15 steps from my front door, and I saw a pot on the side of the road,” Jane Schreibman said. “It looked weird, and I thought it was a kid’s science experiment, with wires coming out of the pressure cooker every which way. I thought someone was throwing it out.”

Schreibman, who lives on 27th Street between Sixth and Seventh avenues, left her home around 10 p.m., after a friend called to tell her about the blast.

She went to investigate but found the roads blocked and couldn’t get the pressure cooker out of her head.

“I had heard the explosion, but I thought it was thunder,” said the travel photographer, who was home at the time. “But I just thought it was going to rain, and I forgot about it.

“The vision of the pot stayed in my mind, and I decided to take another look at this strange object,” Schreibman said.

“It had duct tape, and wires going into the cellphone or remote of some sort. But I couldn’t tell because it was all wrapped up in tape,” the 66-year-old added. “The remote pointed into a white plastic bag.

“They’re always saying if you see something suspicious, you should call, so I did.”

She then left her apartment to watch for the cops and was alarmed when the NYPD bomb squad arrived.

“A man, I guess he was a detective, saw me, and he shouted ‘RUN!,'” Schreibman recalled, saying she went to a friend’s house and played Scrabble. She returned every few hours to see if she could get back on the block — and to her 8-year-old cat, Oceaie, whose cat condo sits next to the window.

“I was really worried about him,” she said, adding that neighbors had all gotten alerts to stay away from their windows.

Finally, around 3 a.m., she spoke to a detective who escorted her home to Oceaie.

The shutterbug said she wasn’t frightened to return home in the wake of the blast, given that she’s seen worse — like the Ayodhya riots of 1992 in India — during her travels.

“It was still such a weird thing,” Schreibman said. “I can’t believe it was really a bomb.”

The pressure cooker was removed by the bomb squad and transported to the NYPD’s firing range in the Bronx.