The 18-year-old has a hectic workload juggling school and sporting commitments with a part-time job at Warren's Garage.
But "in the small spaces left between school, sport and work", Lachlan tinkers around in his garage like Burt Munro, building jet engines.
"I have already built my own very basic jet, based on a turbocharger and currently I'm designing - and hopefully going to build - a more modern and complex engine."
When it comes to setting goals, Lachlan is literally shooting for the stars.
He wants to become an aerospace engineer and already has the route to success plotted out.
He will launch his career by studying astronomy and mechanical engineering at Canterbury University and then travel overseas to study the dynamics and principles of aerospace engineering.
"Once I have completed my goal, I plan on finding work in an aerospace industry outside New Zealand.
"My dream is to bring such a company back home, because I want to see New Zealand working with other countries in space exploration."
It is no surprise Lachlan was first in science in 2006, but he is also a prominent sportsman.
He is vice-captain of the school's 1st XV rugby team, a member of the senior hockey team and has been the school's athletics and swimming champion for the past two years.
Achievements: Built his own jet engine (2008); house captain, Peer Support leader, rugby vice-captain (2008); U16 Most Valuable Rugby Player (2007); senior hockey, school athletics and swimming champion (2007-08); 1st science Level 1 (2006).
Role model: Bruce Simpson. "He's a back yard, DIY guy who builds jet engines."
Hopes for the future: To become an aerospace engineer.