FOR a long time, travel trailers came in two basic varieties: the big white shoebox or the Chiclet-shape pop-up; Airstream's iconic aluminum bubble was a notable exception.
The shoebox still makes a large footprint in the travel-trailer market, but as overall sales have grown since 2005, to 165,100 conventional and pop-up trailers last year, some manufacturers have found success with more adventurous designs.
Yet finding the market's sweet spot is trickier than backing into a campsite. A Dutch start-up, Your Suite In Nature, attracted attention in 2010 with a pop-up that opened into a canvas approximation of the Sydney Opera House.
The Opera was stunning and well appointed, but at 33,000 euros (more than $40,000) it was quadruple the average price of a pop-up. Manufacturing ceased in March after only nine Operas were produced. In an e-mail, the company's founder, Rob Vos, cited high production costs as well as low sales.
Yet the passing of the Opera hasn't prevented other trailer companies from trying to break out of the box. Here are five other head-turning trailers:
EVERGREEN ELEMENT A radically raked front end helps to make this trailer, from EverGreen Recreational Vehicles of Middlebury, Ind., a bit more aerodynamic than most.
Inside, the Element looks like a crew compartment on "Star Trek: The Next Generation": there is a lot of blond wood, rounded edges and flush-set appliances.
The manufacturer's suggested retail price is $40,000, about twice the price of the average conventional trailer. But EverGreen's chairman, Kelly Rose, said the price reflected the use of composite materials, rather than wood and particleboard. "Composite won't mildew or rot," Mr. Rose said. "It just won't break down, and that keeps the Element's resale value high."
TAXA CRICKET Part traditional hard-walled camper and part canvas pop-up, the 15-foot Cricket was created by an architect who helped design the living quarters of the International Space Station.
The manufacturer says the creases and angles of the exterior make the Cricket structurally sturdier and cause less mileage-sapping aerodynamic drag. They also make it look like the crumpled box an expensive wedding gift came in.
The company's founder, Garrett Finney, an architect and former NASA employee, is quick to admit that the Cricket isn't for everyone. But he said it was sold out through November. Prices run from $14,500 to $18,000.
AIRSTREAM INTERNATIONAL STERLING While not averse to innovative design, Airstream has been stung when it strayed from its polished aluminum shells.
In 2005, it teamed up with Nissan Design America to create the Basecamp, which resembled Boba Fett's helmet in "Star Wars." Bob Wheeler, the president of Airstream, said the Basecamp was discontinued when it failed to attract buyers.
Although Mr. Wheeler said he wouldn't rule out another experiment like the Basecamp, his focus for innovation is now on interiors. This includes a radical new interior design introduced last spring for the 2013 International Sterling, which starts at $84,000.
The Sterling began more than a decade ago as a commissioned concept by the designer Christopher C. Deam. The interior is strikingly un-Airstream, with high-contrast color combinations, electric hues, brushed aluminum and pregnant curves.
JAYCO SEISMIC The innovation here is room. A virtual McMansion on wheels, the Seismic has its own garage at the rear, though that space -- from 80 to 112 square feet, depending on the model -- can be used instead as a spare bedroom or a workshop. The back wall can be swung down to do double duty as a patio.
Seismic prices range from $71,000 to $130,000.
A so-called fifth-wheel trailer, the Seismic is pulled by a pickup using a hitch similar to those used on semitrailers.
MOST FUTURIA SPORTS + SPA Speaking of big rigs, this 48.6-foot-long trailer may be the closest thing to a bachelor penthouse on wheels.
A product of MOST, a German maker of custom mobile showrooms and conference centers, the Futuria has a garage big enough for a Dodge Viper and a heated spa tub sunk into the "rooftop viewing area." Options include king-size beds, under-floor illumination and a fog machine. In an interview over Skype, Günter Hofbauer, MOST'S founder, said he sold three or four of the models a year, starting at $850,000.
"It's a crazy product!" Mr. Hofbauer said with a laugh. "Where is the kitchen? Men don't need a kitchen. They need a microwave, refrigerator, a sink. We have that."
This article originally appeared in The New York Times.