The 3.5-metre model has been unveiled to mark the the 150th anniversary year of the iconic Victorian building in Edinburgh.
It took Warren Elsmore and his team 350 hours to create the model, which is built to “minifigure scale” so that Lego figurines look “correct” inside it.
The model features a cross-section of the building showcasing the attraction’s famous Grand Gallery and museum objects including a Formula One car driven by Jackie Stewart and a statue of steam engine inventor James Watt.
Mr Elsmore, 39, who has been building Lego models full time since 2012, said the project was one of his most challenging to date.
The artist, who has had a passion for Lego since he was four years old, said: “It has been a very interesting project but very complicated and challenging – there was so much detail we had to get in there.”
Work began in January, with Mr Elsmore building his model in the museum two days a week so that members of the public could follow its progress and ask questions.
It was then taken to his studio in the south of Edinburgh where he applied the finishing touches ahead of today’s unveiling.
The model now has pride of place on level three of the museum, next to the Balcony Cafe, and will be stationed there for the foreseeable future.
Mr Elsmore said: “While we were building it, a lot of people were stopping to watch us and were asking questions.
“I think the most challenging part was building some of the artefacts and the sculpture gallery – for example the Tyrannosaurus and the Formula One car.
“We’re very pleased with the results and we can’t wait to see what the visitors think now that is on show.
“When it was unveiled it was lovely to see the expressions on people’s faces.”
Stephen Allen, head of learning and programmes at National Museums Scotland, said: “Our visitors have enjoyed watching Warren and his team build our model museum as part of Build It! Adventures with Lego, and we’re delighted to now unveil the finished article.
“From the Victorian architecture of our Grand Gallery to the crisp, clean lines of the modern Scottish Galleries, the bustle of the Balcony Café to the wonder of our Natural World galleries, the museum has been rendered perfectly in miniature.”
Construction of the museum began in 1861 after the foundation stone was laid by Prince Albert. The building opened in 1866 and was finished in 1888.