The final test was a blunt one. Maarten Logtenberg wielded a sledgehammer, which simply bounced off the sample, barely leaving a scratch.

After two years of experimentation, the material was finally right: a particular mix of thermoplastics and fibreglass that is strong, has no need of extra coating to protect it from sunlight, and is resistant to fouling and marine growth.

The perfect base, says Mr Logtenberg, from which to 3D print a boat.

Boats need to withstand the unforgiving nature of the marine environment. It's one of the reasons why boatbuilding is a notoriously labour-intensive business.

But after months of tweaking the chemistry, it took just four days for the first hull to roll off the printer at the new factory that Mr Logtenberg and his colleagues run.

"We're automating almost 90% of the boat-building process, and in superfast time," he says.

"Normally it takes weeks to build a hull. We print one now every week."

It's the kind of story that 3D printing has long promised. A quick, labour-saving production process that drastically reduces costs.

Those promises haven't always been fulfilled – but Mr Logtenberg is convinced that the maritime sector is one where 3D printing, also known as additive manufacturing, can play a transformational role.

Mr Logtenberg is the co-founder of CEAD, a company that designs and builds large-format 3D printers at its base in the Dutch town of Delft.

Until now, its business has been to provide the printers for others to use, but with boatbuilding CEAD decided to get involved in production as well.

"3D printed boats still need to be accepted by the market," says Mr Logtenberg.

"People are not going to invest and then just hope that the market will develop. They would rather buy in capacity first. [So] instead of just........

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