A sketchbook is an artist’s diary: a private, intimate work that’s rarely shared with the public. That’s why the “Sketchbook Show 2016” at Koa Gallery in Kapiolani Community College is so unusual. There are 75 sketchbooks from 42 artists on display, curated by gallery director David Behlke.

It’s an experience in spontaneity and a lesson both in inspiration and the time and drafts that grow into a finished work. Visitors can turn the pages, getting inside peeks at portraits in charcoal, half-finished pencil sketches, self-directed messages (“DON’T PANIC”), ticket stubs and miniature watercolor landscape paintings.

In a walk-through at the gallery, Behlke said he came up with the idea three years ago. This is the second time he’s shown artists’ sketchbooks, and he plans to continue every other year and try to feature artists from all walks of life and at different stages in their careers.

This year, the variety of backgrounds is illustrated by the inclusion of Norm Foster, a musician in the Hawai‘i Symphony Orchestra; Kevin Diminyatz, a Hawaii island printmaker; Spencer Chang, a retired architect with an eye for painting buildings; and others.

The sketchbook show is also interactive: The audience gets to participate by leaving handwritten Post-it notes in the books that the artists can read when they get them back.

“Exhibits are usually a one-way street,” said Behlke. “These little notes personalize things: We can send feedback to the artists.”

In Chang’s watercolor plein-air paintings of Japan, a viewer wrote, “You make Japan look more beautiful than it already is!”

Chang’s sketchbooks are journals of his trips around the world, made first with pen and ink and then watercolor. Esther Nowell is another painter with a travel journal on display. While Chang gears more toward monuments, buildings and landscapes, Nowell has an eye for people. Her journals are almost all in mixed media, with ticket stubs, paintings and photographs placed side by side.

So, was it hard to get hold of these sketchbooks?

“Depends on the person,” Behlke said.

Take Juvana Soliven, a sculpture instructor at the University of Hawaii at Manoa and former KCC student. Her sketchbook is deeply personal, documenting her life for about half a decade; she said she had to take six pages out before giving it to Behlke. Flipping through the pages feels voyeuristic: There are beautiful, yet disturbing and edgy, abstract cartoons and sculptural figures. Included are a semester class schedule, a budget, a travelogue of her European adventures and a whole page of curse-filled rants.

“As you look through Juvana’s sketchbook, you can see that her mind is wonderful,” said Behlke, who said he sat down for an hour and a half, engrossed in Soliven’s sketchbook. “She conveys her own angst without being corny — it really grabs you.”

Another fearless artist, Bernie Moriaz, adds white-out and stencils to zany, fun portraits in bright, colorful paint that jump out of the page. In contrast, Ka-Ning Fong, an art instructor at UH Manoa, has gorgeous nude figure drawings that are quietly empathetic and so full of emotion that they are almost like psychological studies.

There are many more artists, too many to feature here, so go and see this show. It’s a rare opportunity and a privilege to flip through pages of raw, unedited works of art and to glimpse creative minds at play.