Alex, who is homeschooled, completed his building in the last six days of the competition.
"When I saw the competition had been extended I decided to enter. I spent about three hours a day working on the building and on the last day spent about six hours, with the help of my younger brother."
Alex said creating the museum seemed daunting at first but once he started breaking it down into sections using Google Images, it became easy.
"It's a very symmetrical structure so after I had done one side, the other could be copied."
Media Design School communications manager and Pick and Shovel Community manager Rebecca Emery said there were entries from around the world but Alex's stood out immediately.
"The attention to detail and accuracy with which he has recreated an iconic Kiwi landmark is absolutely amazing. We admired his passion for this building, and through his creation, Alex has also helped others all over the world understand more about this important New Zealand icon."
Click the image for Alex's Minecraft tips
Ms Emery said the competition was one of the ways to showcase Minecraft as a learning and teaching tool.
"This competition demonstrates how young people can learn while creating. We believe in the power of games as an education tool and we hope it has inspired Alex to pursue a career in the creative industries, he certainly has the right skills and passions for it."