A lifelong tinkerer, Lass fell into watches after flipping through a university course catalog while studying mechanical engineering in Copenhagen. One day at the local library, he rescued a copy of George Daniels' book Watchmaking from the throwaway bin – and before long, he was enrolled at the one watchmaking school in all of Denmark.

Lass tried the program out for a couple of months – learning the craft of repair and restoration. Realizing that the life of a repairman was not for him, he became an apprentice for Denmark's own Søren Anderson, who among other things, worked on Jens Olsen's World Clock – an engineering feat made of some 15,000 parts. 

During his apprenticeship, Lass met (and then worked for) renowned independent watchmaker Vianney Halter, who taught him how to make a watch from the ground up. In the ensuing years, Lass spent evenings in the workshop of one Philippe Dufour, who filled him in on a rare opening at Patek Philippe. The brand's museum was looking for a master watchmaker. 

At Patek, he refined his skills, serving quite literally as the sole watchmaker in the Patek museum (a fact he hadn't fully processed when he was interviewing for the position). He spent the next near-decade taking historically significant watches apart and learning how they worked. "That is the best experience I had, working in the museum," Lass says. "I was able to study five centuries of watchmaking and see what is good and what is not – to see the style. That was really a unique opportunity."