I remember videos about this project from many years ago. His plan was to make the chimney puff a ring of smoke. Seems it took longer to finish than anticipated
"It is correct that Peter Madsen worked on the prototype for BIG back in 2014 in his capacity of a welder," a company spokesperson told AD PRO.
https://www.architecturaldigest.com/story/blarke-ingels-pete...
Maybe somebody overstated when talking to the journalist, or maybe the company understated his position in some short of PR movement...