SunRay Kelley, the barefoot maverick builder of fantastical handmade castles, yurts, temples, spirit lodges, tree houses, pavilions and structures so fanciful that they defied conventional building typologies, died on July 16 in Sedro-Woolley, Wash. He was 71.

Bonnie Howard, Mr. Kelley’s longtime partner, said that he had been suffering from cancer but that the cause of his death, in a hospital, was a blood clot from a recent operation.

Mr. Kelley was a hero in the world of unarchitected, alternative and vernacular building — a building movement distinguished by its handmade ethos, sustainable features and natural materials, which flourished in the counterculture years of the late 1960s and early ’70s but flagged a bit during the Reagan era.

For the last few decades, however, it has enjoyed a steady, if slightly fringe, resurgence as the costs, both environmental and financial, of traditional housing continue to escalate; new generations of back-to-the-landers and anti-consumerists of all stripes now cleave to its tenets.

Mr. Kelley’s whimsical, Tolkienesque designs were often featured on websites and blogs devoted to tiny houses and other environmentally friendly dwellings, as well as on television shows like the Discovery Channel’s “Building Off the Grid.” He was the go-to guru for people looking to build their dream yurt or tree house, and for spiritual centers looking for a certain mystical flair, as well as a sought-after speaker at natural-building conferences.

“There was no one like him,” said Lloyd Kahn, who has been chronicling handmade habitats in a series of books for his company Shelter Publications since the early 1970s, starting with “Shelter,” an engaging encyclopedia of vernacular architecture — and an early counterculture primer — which was first published in 1973 and is still in print. “There’s no other natural materials builder in the world who’s combined such ecology, design and craftsmanship in so many buildings on the American landscape.”

“He always said Mother Nature was his inspiration,” Mr. Kahn added, “which sounds woo-woo, but he really was tuned in to the spirits of nature. And his work wasn’t put together in some sloppy hippie style. They were extremely well-built masterpieces.”

His constructions were complex and improvisational; he worked from drawings, but he also worked spontaneously, evolving his designs in the construction process. “Evolutionary design,” he called it.

His buildings had undulating peaked roofs, or roofs shaped liked wings or the prow of a ship. They were often planted with sedum, moss and trailing nasturtiums (green roofs are naturally cooling). He loved cupolas and turrets. His preferred shape was the circle, which he felt was nature’s most resilient form; hence the preponderance of yurts in his oeuvre. He was a master of cob, a sturdy, thermally efficient sculptural material made from mud, sand and straw that has been used around the world for millenniums.

Other favored building materials were scavenged and used as they were — unmilled windfall trees, gnarled branches, rocks and boulders. “God’s hardware store,” Mr. Kelley called the woods of the Pacific Northwest, where many of his buildings were made. “I’m going shopping,” he would say in the middle of construction, striding off into the wilderness.

He made some 70 structures, mostly in North America but with a smattering in Central America as well.

The real showplace for his eclectic work and methods, however, was his own property, nine acres in the foothills of the Cascade Mountains in a former mill town in Washington State that had been in his family for three generations, a homestead otherwise known as SunRay shire, or simply the shire.

There one will find the soaring, shingled “Sky House” and the funky “Earth House,” his first effort, with cast bronze hands that support the roof beams; a hermit hut built on the massive stump of an old growth tree; numerous ponds and waterfalls; and a collection of yurts large and small, including one sparkly pink number fashioned from cob flecked with mica and festooned with the sculpted forms of the female body; an enormous anatomically accurate representation serves as its doorway. This particular yurt was designed for yoga practice; Mr. Kelley called it the Yogurt.

The compound has for decades drawn alternative-building pilgrims, whom Mr. Kelley would often cajole into work duty. Michael Tortorello, writing in The New York Times, described the place as a hippie Taliesin, referring to Frank Lloyd Wright’s home and studio in Wisconsin.

With his peaked felt caps, exuberant white mane and dreadlocked beard, dusted with bits of straw and wood, he presided over it all like a burly woodland wizard — except that instead of a wand he brandished a chain saw. A man constantly in motion, he wasn’t exactly accident prone, but he did throw himself into his work, and he nearly lost a few body parts in the process.

He was a sculptor first and a builder second, said Ms. Howard, who has collaborated with Mr. Kelley for two decades. She would look over his shoulder as he sketched and add function to the form: closets, for example, and light switches.

The couple met in 2004, when Mr. Kelley was building what might be his magnum opus, an exquisite retreat center called the Temple at Harbin Hot Springs in Middletown, Calif. Essentially an enormous yurt, it was made from straw bale and cob walls topped with an artful spiral ceiling and a peaked roof clad in shingles laid in a wavy pattern, like the ridges of a scallop shell. (The temple was razed by the wildfires that swept through Middletown in 2015.)

Ms. Howard was attending a workshop on cob and straw bale construction led by Mr. Kelley, the end result of which was to build the retreat’s walls. To make cob, fiber like straw is mixed with mud, either mechanically or by humans stomping it in with their feet. It was that method Mr. Kelley taught his students. Since Harbin Hot Springs is clothing-optional, they worked naked, which is more practical than the alternative, Ms. Howard said; it’s easier to wash mud off your body than your clothes.

Ms. Howard said she fell in love with both the mud and the man.

Raymond Elbert Kelley, one of five children, was born on Dec. 1, 1951, in Sedro-Woolley, a logging and mill town. His father, Cecil, was a mechanic in a mill. His mother, Wanda (Janicki) Kelley, was a homemaker who baked her own bread and churned butter; her parents, Polish immigrants, had homesteaded the land Ray grew up on. The family raised beef and dairy cows.

Ray studied drafting in high school and attended West Washington University on a football scholarship. He studied art there but dropped out after two years and started designing buildings. When he showed his swirling sketches to a local builder, he later recalled, the man said, “You better get a hammer, boy, because nobody is going to build this stuff for you.”

In addition to Ms. Howard, Mr. Kelley is survived by a brother, Tim; a daughter, Kumara Kelley; three sons, Rafe Kelley, Kai Farrar and Eli Erpenbach; and seven grandchildren. His marriage to Judy Farrar, in 1978, ended in divorce.

Mr. Kelley lived by a few credos, which included what he called “barefootism” — he adamantly eschewed footwear, believing that being barefoot was a grounding behavior that connected him to the earth’s energy, no matter the weather.

Ms. Howard recalled buying him a pair of boots one winter early in their relationship, and coming home one blizzardy day to find the boots by the door where she had left them and a track of footprints leading away from the house and disappearing into the deep snow.

“Dessert first” was another mantra. Mr. Kelley’s habit was to eat dessert before dinner, and he did so with terrific gusto — Mr. Tortorello of The Times recalled him enjoying a hot-from-the oven apple crisp with his bare hands. “His line,” Ms. Howard explained, “was, ‘You never know when your bubble’s going to pop, so eat dessert first.’”