When he was 17 years old, Jack Ryan would take a pad and pencil down to a salvage yard beneath the Brooklyn Bridge in New York city and draw the cityscape that towered above him. Over the heap of junk he could see the skyline of lower Manhattan piercing the clouds, architectural marvels he would depict on paper, one miniscule dot at a time. Once finished, hundreds of thousands of the dots would coalesce to form the scene, a black and white illustration as accurate as a photograph.

Mr. Ryan, now 61, is one of the friendly faces behind the counter at the West Tisbury post office, where he’s passed along mail for the last three years. Since moving to the Island in 1986, he’s spent his days mostly as a house painter before getting a job at the post office. His nights, though, have never changed. After work, Mr. Ryan spends upward of six hours each evening at his drawing board in his studio, pen in hand, delicately dotting a sheet of paper.

Mr. Ryan grew up in the shadow of Manhattan, working for a time as a bike messenger.

Mr. Ryan grew up in the shadow of Manhattan, working for a time as a bike messenger.

“I do it every night,” he said. “I come home from work, have something to eat, and am in the basement drawing. It’s calming. When one of these drawings is coming together, it’s wonderful. Right up to that time I’m not sure if it’s going to look right . . . when I start getting close to the end of a drawing I start getting real nervous that my pen will explode or something.”

Mr. Ryan, Brooklyn-born and raised, honed his pointillism technique at the High School of Art and Design and the Pratt Institute in Manhattan. He tried other mediums, but in the end only one of them stuck. His overhead is just a pen, paper, a bottle of ink and lots of erasers.

“I tried everything. Airbrush, painting with oils, acrylics, watercolors...I always came back to this,” he said while holding up a pen about as thick as a Sharpie but with a point as tiny as a needle. “It’s just so much fun to draw stuff with these things.”

The tool is a Rapidograph technical pen with a point just .13 millimeters wide, the smallest in Mr. Ryan’s collection. No longer climbing around scrap heaps, he now takes his inspiration from old postcards or photographs of iconic New York city structures. The dotting is methodical and meditative, and Mr. Ryan said breaks are often required during the over 200-hour process of drawing one of his pieces.

“It’s like I’m doing a crossword puzzle,” he said. “If I get frustrated I take a break and come back to it. It doesn’t feel like I’m exercising any type of patience at all. It’s the only way I could get something like this done. I’d mess up the whole process if I tried to rush.”

Though Mr. Ryan never pursued a career as an artist, his work has made it onto the pages of international publications and in New York city galleries. His work has also been featured on greeting cards, including a Christmas card for the Museum of the City of New York, and the thank you notes for anyone who donated to the Gay Head light relocation in 2015.

Mr. Ryan's wife, Lauren, supports him when he gets stuck on a piece, helps him put it back together and helps hang his shows.

Mr. Ryan's wife, Lauren, supports him when he gets stuck on a piece, helps him put it back together and helps hang his shows.

In New York he worked for a time as bike messenger, navigating the densely packed Manhattan streets to deliver Marvel Comics sketches from artists such as Stan Lee and Jack Kirby. In his free time he climbed to the top floor of buildings to photograph aerial scenes for his next drawing.

In 1997, he ascended the Chrysler Building, all 77 stories of it, but there was only one way to get the shot he was looking for.

“I looked at my buddy and said why don’t you hang me out the window with that rope?” he said. “I realized after that there was only one snap holding the belt!”

After struggling to afford the high costs of city life through various odd jobs, Mr. Ryan moved to the Vineyard and married his wife Lauren, a post office clerk at the Oak Bluffs office. When he gets stuck on a piece and thinks about tossing it out, he said it is Mrs. Ryan who helps piece the work back together. He said she also helps hang up his drawings whenever he’s opening a show.

“Lauren is my biggest supporter,” he said. “I’ll be doing a drawing and something’s not clicking, I’ll bring it to her . . . without her I’d be lost.”

The exhibit is at the Vineyard Haven Library.

The exhibit is at the Vineyard Haven Library.

It’s been a long journey from that time under the Brooklyn Bridge to the studio basement of his Oak Bluffs home, but Mr. Ryan said he couldn’t be happier. He said the days in the post office are full of laughs with his coworkers and customers and he wouldn’t trade it for anything.

“I thought I’d never adapt,” he said. “I’ve never worked behind a counter before and I was scared to death. The customers are the most eclectic, amazing bunch of people I’ve ever encountered. I’m very proud of what I do at the post office. The people I work with couldn’t be better.”

He added that sharing the name Jack Ryan with the action star of Tom Clancy novels and a new Amazon TV show has given him a chuckle every time he sorts a new Amazon package.

“It’s hilarious. Every other Amazon package that comes to the post office has my name on it,” he said. “But I’m the only Jack Ryan in Oak Bluffs.”

Mr. Ryan has had three exhibits this summer. His latest show runs through Sept. 30 at the Vineyard Haven Library as part of the Art in the Stacks program. He said he hopes the show inspires people to pick up that long-forgotten paintbrush or pen and make time each day for their craft.

“If you are moved by drawing, painting, whatever . . . just nurture it and hone it and never stop,” he said. “I think it all boils down to if someone wants to draw and feels really passionate about it, that’s more than half the battle. Then all you have to do is sit down and hone it.”