Minnesota man builds castle with 3-D concrete printer

With just the click of some buttons, a 12-foot-tall castle has appeared in a quiet Minnesota back yard — proof of the very latest in technology.

Andrey Rudenko built the castle layer by layer with one of the first 3-D concrete printers in the world, an ambitious task given that most things produced by 3-D printers are much smaller, like plastic models or parts. Now the Shorewood engineer and contractor has an even larger goal: use his 3-D printer to build the first-of-its-kind concrete house.

"Every time, it's getting bigger and more complicated," he said of his creations. "It's just magic for me."

3-D printing has emerged in recent years, bringing the futuristic concepts to reality with everything from luxury cars to toy puzzles to the latest fashion. Researchers are even working to perfect printing human body parts.

And the Twin Cities is on the cutting edge of it.

Eden Prairie company Stratasys makes 3-D printers for everything from consumer toys to prosthetic arms and wax-ups for dentures. Maple Plain-based Proto Labs started selling 3-D printed plastic and metal parts, mostly to engineers, this year.

But in the Lake Minnetonka suburb of Shorewood, Rudenko is forging his own path in technology that's so new there are few guides or tutorials to follow. With a background in engineering and design, the building contractor started experimenting with 3-D printing two decades ago. When the latest technology emerged a couple of years ago, he said, "Wow, it's time to start experimenting again."

While most 3-D printers produce smaller plastic objects, Rudenko wanted to create a concrete printer for large structures to be on the cusp of what he says could one day be the norm in home construction. It took him two years of work — and one minor garage fire — of tinkering with designs to make his printer, made up of rails, beams and a control box that uses computer designs to "print" various shapes. It's a process less like printing paper and more like a manufacturing robot, squeezing out concrete, layer by layer.

Rudenko started producing concrete boxes — the first one, a rough rectangular. Over time, he smoothed out the lines, revised the concrete mix and designs and, with more than $1,000 in materials, he started work on his first big test of the technology: the castle.

Heavy rain in the Twin Cities this summer and dealing with the new technology delayed the project. Instead of completing it nonstop in three days, Rudenko said, it took three months. Last week, he finally wrapped up building the 7-foot tall castle with three towers and arched windows — part Gothic castle, part Disneyland. It's the first concrete 3-D printed castle in the world and the first 3-D printed concrete structure in the country, he said.

While the back-yard castle has created quite a buzz in his quiet residential neighborhood, it may not be used much as a children's castle by Rudenko's 7- and 19-year-old kids, but instead is evidence of what Rudenko said he can accomplish. "I can show it to people as proof of the technology," he said.

It's already gaining him worldwide attention from architects and artists interested in concrete 3-D printing. And Rudenko said he hopes it will help him get hired to produce the first concrete 3-D house, made in one piece in less than a week.

He planned to build it in Minnesota, but with winter approaching and 3-D printing not certified for housing in Minnesota, he said he's looking to build it in a warmer state. "I'd like to build something special here," he said. But "it's just new technology; no one knows what to do."

The housing market would benefit, he said, from less expensive, more energy-efficient, recyclable homes that wouldn't even need Sheetrock or much manual labor.

"All of my mind is on the next project," he said of not celebrating the castle's completion. "The printers are just beginning."

Kelly Smith • 612-673-4141

Twitter: @kellystrib