There isn’t a single “Do not touch” sign up at Martin Katz’s exhibition at the Interior Niche gallery. The Menlo Park sculptor wants visitors’ hands all over his art.

It’s true, Katz’s shapely bronze and alabaster pieces — an expressionistic David, a saucy college girl at the bus stop, a miniature Henry Moore-like female figure — do feel good to the touch.

But one piece now on display at the San Francisco gallery Interior Niche seems to call out more than others: Katz’s life-size bronze Torah scroll, which he calls “The Moebius Loop Torah.”

As we all learned in seventh-grade math, a Moebius strip is that curious one-sided surface resembling a figure eight. It suggests infinity, boundlessness, eternal cycling back.

Kind of like the Torah.

“The concept was a continuum,” says the garrulous 81-year-old Katz. “On Simchat Torah, we don’t say ‘Whoopee, I’m done!’ We say, ‘Whoopee, I can start again.'”

The bronze piece features two “wooden” scrolls, extended upward like outstretched arms, the parchment in a double twist and, on the base, Hebrew letters spelling out Bereshit (“In the beginning”) and Kol Yisrael (“all of Israel”), the first and last words in the Torah.

Katz’s Torah is on display at Interior Niche, but not for long. Its destination is a new meditation garden at Congregation Beth Am in Los Altos Hills, which is due for completion by the High Holy Days. Katz and his family have been Beth Am members “for forever,” he says, and he couldn’t be happier to have his work a permanent part of the landscape there.

“I thought this would be a wonderful piece for the congregation,” he says. “The art committee loved [the idea] and in November [2007] we were a go.”

Eight days later, he had his model completed. Then it was off to a commercial foundry near Monterey to have the Torah cast in bronze, an intricate 4,000-year-old process that fascinates the sculptor.

It’s no surprise Katz delights in the science of bronzing. He is a retired drug industry executive with a background in chemistry and pharmaceutical research. Katz is one of the people responsible for developing the birth control pill and the analgesic Naproxen (next time you take Aleve for a headache, thank Martin Katz).

The Brooklyn native traces his first artistic impulses back more than half a century, when he and his wife, Lee, would traipse off to art museums. “We’d go to the sculpture exhibits and I would say, ‘What’s the big deal? I could do that.'”

But for many decades, he had no time for art. Katz became a senior executive with the international drug company Syntex, which sent him west to head up Northern California operations back in 1964.

Tragedy struck in 1981 when Katz’s son took his own life. To cope with that calamity, Katz began studying sculpture. Turned out he was right: He could do that. “The work was simply for fun,” he explains. “It was a hobby that became a serious avocation.”

Though his work runs the gamut from realism to expressionism, Katz has done only one other overtly Jewish sculpture.

It’s a figurative piece of mourners, inspired by the loss of his son. Katz calls it “Yizkor.” In 2002, it was chosen to be part of a 9/11 commemoration exhibition. Today the piece remains in the Katz home, where it will stay.

Katz says he’d like to do more Jewish-themed work. He has an idea for a burning bush piece, and another based on the Ten Commandments that he says “has never been done before” (though presumably he won’t display it at a courthouse).

Katz might be in his eighth decade, but he lives a very active life. He and his wife, a retired economics professor, have been married for 61 years and have two daughters and five grandchildren. He still skis, plays tennis and does consulting work in the drug industry.

When asked to draw parallels between developing a prescription drug and making art, Katz says both are all about problem solving.

Which is why, when he first contemplates a piece of stone or clay, Katz asks himself the most salient question: “What do you think is in there?”

A reception for sculptor Martin Katz will be held 2 p.m. Sunday, Sept. 21, at Interior Niche, 3535 Sacramento St., S.F. His pieces will be on display through December. Information: (415) 567-1466. To view Katz’s work, visit www.martelier.com.