Andrey Rudenko used an enormous 3D printer to build a full-sized castle.

If you're at all interested in 3D printing, you probably know that already, but what you might not know is much about the man behind the printer which used concrete to create this startling structure.

Rudenko is a contractor with a background in engineering who, working from his garage in a Minneapolis suburb, has doggedly pursued the idea of using 3D printing to devise a practical system to build practical homes.

Rudenko has been applying his efforts at concrete for about the last 20 years, and though the computers and software he used at the start of his quest weren't up to the task at the time, a couple years ago he discovered the RepRap project and a lightbulb lit up over his head.

"The 3D House printer is a result of experience I gathered over the years working in the design and construction field, experimenting with different tools and equipment," Rudenko says. "No surprise here, but I was always passionate about things like electronics, computers, and of course, cool architecture."

As a child, Rudenko was fascinated by the latest technology and his hobbies reflected those interests: soldering circuit boards, fixing electronics, radios and TVs and building custom bikes to hone his mechanical skills.

"All my previous experience came in handy when constructing my printer," he says.

With his degree in engineering and a passion for interesting architecture, Rudenko then began collaborating with architectural firms on a series of projects on exterior and interior designs for museums, unique residential homes, mansions and hotels.

"These projects allowed me to use my knowledge of electronics, architecture, and mechanics to make custom-made equipment not available in mainstream markets," he says. "I had to learn about using a variety of materials, such as wood, metal, concrete and plastic. I was always searching for new technology to make the process more efficient and easier since existing technology is labor-intensive and outdated."

Noting that the last major innovations in residential construction are nearly 100 years in the past, Rudenko says he looked to construction methods in different countries for inspiration. In the way that some travelers learn about food and wine by crisscrossing the globe, Rudenko surveyed the most interesting technological and architectural practices on offer.

"A few years ago when I saw the RepRap project, the pieces – my knowledge, experience and interest – all came together in the 3D House Printer," he says. "The concrete printer is only one piece of a new construction system and concept I envision and hope to develop for the future. 3D printing technology is in high demand and is spreading quickly. There's no doubt that in a few years, we'll see many construction companies using 3D printing technology to modify the traditional way to build."

Completing the current system did, however, pose some specific challenges. Rudenko says that a small, simple 3D printer can print on a table, but printing on a large scale "changes everything."

"Printing a house is highly regulated and has a lot of complications tied into it. You must meet codes and apply for certifications and licenses. You also have to ensure the printer is weather-resistant, but at the same time, portable enough to be moved," he says. "Prototyping such a huge machine gets expensive. Successful completion of the castle project proved the technology. Now my short-term goal is to complete my next project – printing an entire house. My long-term goal is to build printers and printer kits which would allow 3D printing to be utilized by people around the world."

Driven by the Arduino Mega 2560 board and software common to a variety of 3D printer kits, Rudenko incorporated large motors to make a device capable of extruding layers 20 mm wide and 10 mm tall. A concrete and sand mixture solidifies quickly enough to make the process practical. By "free-layering" the fine concrete mixture, Rudenko's printer outputs walls which require no finishing tools.

Eventually, Rudenko says his buildings will include plumbing, electricity and insulation as part of the construction process. He also has plans to evangelize for his process by inviting architecture and engineering students to see his process at work