What’s that old chestnut? “Idle hands are the devil’s tools”?

Well, Aimee Mann may not subscribe to that old saw, but she definitely is not one to stay idle. Since 2008, when she released her last album — “@#%&! Smilers” (“you can provide your own curse word there," she says) — Mann has been one busy writer.

For starters, she’s tackled the huge undertaking of adapting her 2005 concept album “The Forgotten Arm” into a stage musical. She’s already written 10 new songs for the production; is working on writing the “book,” or script; and is planning how to adapt the album’s songs for the stage.

“The songs are farther along than the book, and the musical style we’ll be using is still evolving,” Aimee Mann says during a recent phone interview. “In some respects, it will be similar to the production on the album, but I also like old-fashioned Broadway musicals, so some of it may have those kinds of arrangements, with horns and strings….”

Mann comes to The Ark on Tuesday for a sold-out show.

The songs on “The Forgotten Arm” album, which was produced by the ubiquitous roots-rock producer Joe Henry, tapped into some of Mann’s earliest musical memories — the disc crackled with early-’70s roots-rock influences.

Mann, who began her recording career as the big-haired lead singer for ‘Til Tuesday, cites early-‘70s Elton John and Rod Stewart as two of her favorites from that era, along with Mott the Hoople and the Band.

“I listened to a lot of that stuff as a kid,” Mann told me back in 2006, when I interviewed her for the Ann Arbor News. “The first time I really got excited about music, it was Elton John’s first few albums — I played those over and over. Plus, Bob Dylan and Neil Young were on the turntable a lot.”

“The Forgotten Arm” was an unflinching but empathetic song cycle about a drug-addicted boxer and his lower-class girlfriend, who meet at a state fair in the South, then hit the road together. Over the course of a year, their relationship deteriorates as he sinks deeper into his addiction.

Mann says she’s always been drawn to those kinds of Southern-lower-class story lines, partly due to growing up in Virginia, and also having lived in North Carolina for a time. She remembers, as a child, having a housekeeper who would sometimes take Mann along for visits to relatives out in the country. “And these folks literally had a dirt floor in their house, and their name was Drinkwater,” says Mann.

Mann figures the musical will probably make its debut in about two years.

But in addition to writing new songs for “The Forgotten Arm” musical — and working on all of the various other aspects of putting together a stage production — Mann has also carved out time to start writing songs for her new album.

“I have a handful of songs written for the next album,” she says, and plans to start recording in November. “So far, there doesn't seem to be a unifying theme to the songs, subject-wise, but my inclination, sonically, is to do a really lo-fi, home-studio kind of record. But that could all go out the window when my producer Paul Bryan and I start playing stuff through and really thinking about it. He's been doing a lot of orchestration lately for other projects, so I bet some of that will show up too.”

Bryan also produced “Smilers,” which had a very different sound than “The Forgotten Arm.”

“I didn’t really have a plan going in to those sessions (for “Smilers”) , but once we got in the studio, and the keyboard player began playing certain kinds of things, I said, ‘’Let’s go in that direction,’” says Mann.

“That direction” was a left turn away from the guitar-driven sound of “The Forgotten Arm.” Mann, Bryan and the band ended up using distorted Wurlitzers, clavinets and analog synthesizers to achieve a hook-conscious sound that was bigger than on “The Forgotten Arm,” but at times, also echoed the wobbly and muffled-groove vibe of the Los Lobos albums that were produced / engineered by Mitchell Froom and Tchad Blake.

“We ended up not using any electric guitars — I liked the idea of using keyboards to get a tougher sound, and juxtaposing acoustic guitars and organic-sounding drums with these analog synthesizers,” says Mann. Some other tunes were punched up by a horn section, while others added texture by using strings. Listen to Aimee Mann "Freeway" (MP3).

The characters Mann wrote about on “Smilers” were alternately forlorn, self-deluded, disconnected or just flat-out depressed by the state of their lives.

“Again, I think that just comes from that part of me that is drawn to writing about the human condition,” says Mann. “Conflict is always interesting, and people who have difficulties have a lot of conflict in their lives. Everyone has their share of problems and unique histories. As a writer, I just think it’s fascinating to see what’s under the surface.”

Although “Smilers” — her most recent album, after all — had a more expansive sound, Mann has not assembled a large band to replicate that sound for this tour.

“No, we’re actually doing a smaller thing this time out,” she says. “It’s stripped down to just a trio — acoustic guitar, keyboards and bass. I’ve used that kind of instrumentation in the past. Playing with a full band, with drums and electric guitars, can be preferable, but I like this, too.

“In a way, just playing with a trio is more musical, because you can really hear the other musicians better, so you can respond more to them. It does take some re-arranging, but all of my songs start out with me writing them on an acoustic guitar. So, in a way, this is just me returning them to their original form.”

Kevin Ransom is a free-lance writer who covers music for AnnArbor.com. He can be reached at KevinRansom10@aol.com.

Aimee Mann performing live in Toronto in 2008: