“I counted them!” says Erna, who spends the critical final stages with all her tools and materials strewn over the living room floor. “Our friends are always very curious but they know that in April and May [leading up to the submission deadline], they’re not allowed to see.”

Originally from South Africa, Karl ran an ostrich farm and Erna was a qualified dietitian before they reinvented themselves after moving to New Zealand in the late 90s. The couple recently completed a block of 35 apartments in Papakura and are now working on a complex residential build using clay blocks, a sustainable material that’s been used in Europe for centuries but is relatively novel here.

Collaborating on WOW projects is what they do in their downtime for fun, counterbalancing the stress of running a business in today’s challenging economic climate, and their complementary skills make for a dream partnership. Typically, Erna comes up with the original concept and Karl nuts out how to execute it. “He’s a genius,” says Erna. “I plant the seed and he lets it grow. I can just say anything and he’ll make it work.”

Well, almost anything. “What happens is Erna gets an idea and then come hell or high water, it has to be done,” says Karl, who doesn’t use any computer-aided design (CAD) tools, making early prototypes from paper or cardboard. “She’s an absolute perfectionist, and sometimes I have to tell her not that even Nasa has the capabilities and budget to pull that one off.”

The real magic happens when movement is added to their flights of fancy at the live show. This is the 12th time the pair have entered the WOW awards, scoring a runner-up prize on debut in 2006.

Over the years since then, they’ve featured in the Bizarre Bra category three times, including one design fashioned from air-conditioning pipes and some old trophies that were presented to Karl’s father back in South Africa when he worked in banking. It was only when the silver plating started flaking off that they discovered the trophies were actually made of brass.

Their 2013 winner, Astrodelic Psychonaut, was made from strips cut from aluminium sheets that quivered when the model walked. Karl worked out the mechanics of that one by dismantling the retraction mechanism of a vacuum cleaner to see how it worked. A later entry, also made from aluminium, weighed 22kg and was worn on stage by a ballerina en pointe.

In 2022, they riffed off the disruption of the Covid pandemic with Unravelling, making three garments on a French loom from recycled and dyed T-shirt fabric that had been stitched together.

“Karl still hates me for that one!” says Erna. “The moment you start to pull it, the whole thing comes apart, so each [model] pulled the other one so they all unravelled on stage. But there were 16 shows, so we had to create those three garments 16 times.”

Last year, Erna took out both the Mars & Beyond category and a second People’s Choice Award with Blooming Proof!, a multi-coloured crochet alien.

Karl decided to bow out of that one, so Erna formed a long-distance creative team with her South African-based mother Joanne and mother-in-law, Lena. Both in their 80s, they helped crochet hundreds of “granny squares”, which were then sewn onto a full-length body stocking.

The finalist designs in this year’s “Dream Awake” show incorporate materials that range from the innovative to the obscure: car parts, human hair, digital waste, antique silk, roadwork safety equipment, old mattresses, lamp shades and gutter guards.

The Van Der Wats’ entry, On the Spectrum, is dedicated to Erna’s teenage niece in South Africa, who has struggled since being diagnosed with autism a couple of years ago. A play on words, the title references both the autism spectrum and the colours of the spectrum. “Getting out and showing your true colours – that’s the whole inspiration behind it,” Erna says.

The design, which was first assembled on a mannequin, survived a near-disaster when it wouldn’t fit on a human model and had to be almost entirely deconstructed. Dealing with last-minute emergencies is something they’ve learned to take in their stride. Last year, the light stopped working in the crochet alien’s eyes, requiring “major lens replacement surgery” to fix what turned out to be a loose wire.

Undaunted, the Van Der Wats already have a concept in mind for next year’s Air category. The couple take obvious pleasure in their WOW collaborations and Karl admits it’s addictive. “When you get into that creative mode, it’s hard to stop,” he says. “It’s almost like a life journey, except we repeat it all over again every year.”

Joanna Wane is an award-winning feature writer on the NZ Herald’s Lifestyle Premium team, with a special focus on social issues and the arts.