Editor's note: This tour of small businesses across the country highlights the imagination, diversity, and resilience of American enterprise.

In 2008, Lea Redmond sewed herself a postal worker uniform; crafted teeny-tiny stationery, teeny-tiny envelopes, and a sheet of teeny-tiny self-adhesive stamps; strapped a miniature roll-top  desk from the American Girl doll collection on her back; and bicycled to a bakeshop in Berkeley, California. Setting up at a table there, she used the finest of fine-tipped pens to inscribe brief notes for patrons, secured the notes in the envelopes with wee wax seals, and deposited them in a diminutive blue and red mailbox. Later she would enclose the missives--along with miniature magnifying glasses--in normal-size envelopes and mail them. Charmed-out-of-their-pants customers paid $3 for the service.

Redmond offered "The World's Smallest Post Service" several more times at area cafes before consigning it to a website. "It was just an art project: something close to my heart," says Lea, who has transcribed birthday greetings, notes from the tooth fairy, love letters, and a few marriage proposals. "I like to make things that help people connect in thoughtful, meaningful ways. If I'd been trying to make money, I wouldn't have thought of it."

Today, Lea is making money from the Post Service--and from more than a dozen other products and services that began life as eccentric projects in her whimsy-wired brain. As co-founders of the gift and promotions company Leafcutter Designs, she and her brother Devin have transformed the kind of aesthetic sensibility typically expressed in experimentally minded galleries and one-off handicrafts into a small but profitable multiproduct concern.

Leafcutter operates out of a converted 1909 grocery store in Berkeley, California, a city stuffed to its liberal gills with makers, creators, and arts organizations. Under 15-foot ceilings, the company's two employees--joined by as many as a dozen temporary helpers around the holidays--pack myriad tiny components into cellophane bags for shipping. More than a hundred small gift shops around the country and overseas offer Leafcutter's products as well as interactive books written by Lea and published by another company under license. In November, Oprah Winfrey named one of Lea's book series among her "Favorite Things."

The Redmonds are also disrupting the dreary promotional-products industry with such adorable takeaways as tiny packages that can be filled with any message or logoed tchotchkes that fit inside a two-inch-square cube. In 2013, PopCap Games introduced a new edition of a Plants Versus Zombies game by distributing 60,000 packets of Leafcutter's "seed money"--embossed paper coins embedded with real seeds that sprout when you plant them.

"We had a new character debuting--Bonk Choy--and they were able to get us bok choy seeds," says Leigh Beach, brand art director for Plants Versus Zombies at PopCap. "We had another new character called Snapdragon, so they got snapdragons. People loved them. Even at Comic-Con that year, people would come up to us and talk about the seed coins."

The Redmonds describe their typical customers as creative souls who lack the time to concoct envelope-pushing marketing collateral or thoughtful, surprising gifts. "We let people express their intellect, their creativity, and their cleverness without being crafty themselves," says Lea.

The Valentine bump.

Devin and Lea grew up in the kind of family that would sometimes play hooky in the middle of the week to visit an art museum. Their home, in a small beach town south of Los Angeles, was well stocked with crayons, paints, and craft supplies. In fourth grade, Lea started making earrings out of characters cut from the Sunday comics--Calvin in one ear, Hobbes in the other--and selling them on the school playground. "I took a bunch of samples to this little gift shop on Main Street," says Lea. The owner "thought it was so hilarious to have a little kid asking if she wanted to carry her earrings wholesale."

Devin, who at 39 is two and a half years older, sold some pairs to girls in his middle school class. "So this partnership goes way back," says Lea.

Lea graduated from Whitman College and then did a stint with AmeriCorps. She dropped out of art school after one semester, convinced that she "could make more art not in an institutional setting and not get into debt."

Shown in a handful of California galleries, her work was interactive, high-concept, and consciousness-raising. For example, she wove a four-foot-long version of the kind of tag typically sewn into shirt collars, including information on country of origin, to remind viewers of the real people and places responsible for making their clothes. She then displayed the outsize tag alongside a large map of the world, and invited visitors to cut off their own clothing tags and pin them to the map where their garments were made. They could then select from a basket of tags crafted by Lea and inscribed with poetic statements honoring far-off laborers.

Devin chose the left-brain fork in the road. After graduating from Williams College with a degree in economics, he worked in management consulting and commercial real estate, then attended business school at the University of California, Berkeley. 

In 2009, Lea was employed by a perfume company, working on personal art projects, and still operating the World's Smallest Post Service online. Devin had created a website through which customers could submit text for their tiny letters, which Lea still handwrote and mailed. By then she was charging $8 or $9 plus shipping: not minting money but at least salting away a small profit. Then, two weeks before Valentine's Day, the website Boing Boing ran an article about the service. "I got a thousand orders in two weeks," says Lea. "I was like, oh, my goodness, I am going to quit my half-time job and take over my parents' dining room."

Around that time, Lea was developing two new projects that--with the success of the post office--she realized were also potentially products. The first was puzzle cards, quirky images of things grafted to unlike things and described by funny hybrid words ("Tornadonut," "Henvelope"). The other was a matchbox theater: like the post office an exercise in miniaturization. The product comprises a matchbox from which a stage pops out; 14 "characters" represented by tiny illustrated flags attached to matchsticks; and a script, which might be wholly original or based on the works of writers like Pablo Neruda, Emily Dickinson, and Henry David Thoreau.

Constructing each theater was magnitudes more time-consuming than transcribing tiny letters. So Lea reimagined the theater as a kit, and borrowed $12,000 from her parents to begin production. A custom matchbox manufacturer was willing to create boxes without strike pads and matches without phosphorous heads, so the theaters would be safe for children. A local printer produced the die-cut stages. And a label maker created the "puppets" that buyers peel off and affix to the matches.

Devin at that time was back working in commercial real estate, feeling unfulfilled. "The more time I spent with Lea seeing the things she was making, the more I thought this is something only I can do with her," says Devin. "We should start a business together and see where it goes."

A thumbs-up from Oprah.

Lea Redmond may have a longer, more layered explanation of her company's name than any entrepreneur in history. An abbreviated version: Leafcutter ants are farmers, and Leafcutter Designs cultivates beautiful things and relationships. The ants use scissor-like mandibles to cut little pieces off of leaves, which is kind of crafty. Ants in general are small, which reflects the company's origins in miniatures and its desire to foster appreciation of small everyday things. "And my name is hiding in the first three letters," says Lea, "which is fun."

"Fun" describes virtually everything at Leafcutter. Its products are meant to promote non-digital communication--"this beautiful human-to-human activity," says Lea. So, for example, Leafcutter makes sets of a dozen wooden dice with different ingredients printed on each surface, so family members can roll to decide what's for dinner. The dice are big sellers at Butter Home, an independent gift shop in Seattle. "They are so whimsical and also relatable--there is nothing else like it," says Claire Corley, the store's owner. "I have friends whose kids were not interested in vegetables, and then they got the recipe dice. Now they enjoy being part of the process."

The siblings have mostly bootstrapped the business, although Kickstarter has been good to them, yielding roughly $100,000 over five campaigns. "It's been an important part of getting us to where we are," says Devin. "Not only for the money it's raised but also the new audience it helped us connect with." (PopCap discovered Leafcutter's "seed money" on Kickstarter.)

In the past few years, 10 to 20 percent of Leafcutter's revenue, which is under $1 million, has come from licensing arrangements with San Francisco-based Chronicle Books and several other publishers. Lea's books are as interactive as her products: They include the Letters to My ... series, a variation on the post office theme. Buyers receive a book containing a dozen blank letters, each with a different prompt meant to inspire a personal missive to a baby ("Your first home was like this ..."); a love ("It's the little things, like when ..."), or one's future self ("I never want to forget this ..."). The letters are meant to be folded, sealed, and assigned future dates for opening, "so it becomes a paper time capsule," says Lea. That series has sold more than 500,000 copies in the United States, buoyed since November, by its Oprah validation.

The company manufactures most of its goods in the United States. A few components, like the miniature magnifying glasses incorporated in letters and packages sent by the World's Smallest Post Service, are sourced in China. The Redmonds' preference for domestic vendors is guided by Lea's interest in connecting personally with those who make her products, something that dates back to her clothes tag art project.

You've got mail.

Through rain and snow and dark of night, the World's Smallest Post Service soldiers on. Now business clients, including real-estate and insurance companies, use the service for high-end direct marketing campaigns. The Toledo Museum of Art custom-ordered Leafcutter's tiny packages--wrapped in brown mailing paper and tied with white twine--as a thank-you for donors to its new wing. Inside, recipients found lapel pins shaped like Alexander Calder sculptures protected by, instead of crumpled newspaper, crumpled miniature blueprints of the new wing.

Businesses "come to us when they want something really special, not just [to] slap the logo on a pen," says Lea.

Lea says she loves all her creative offspring equally. But she is occasionally frustrated that so many of her ideas--she fills notebooks with them--aren't practical for mass production.

"In my mind, I am asking, when do I get to do my teacup lending library?"