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How Marble’s startup studio turns climate problems into deep tech companies—and why founder chemistry, early hires, and culture decide whether you move the needle or fail.

In this episode of Skills, the podcast about the people side of building deep tech ventures, Julien talks to Ben, co‑founder of Marble, a climate hard-tech startup studio.

Marble builds multiple deep tech companies in parallel, starting from climate problems and technical “white spaces” in areas like geothermal, geologic hydrogen, construction robotics, and more.

Ben explains when the work stops being about the idea and becomes all about people, starting with the first founder, and then the critical choice of a complementary co‑founder.

A big part of the conversation is “founder chemistry”: how to spot it, why you can’t fully engineer it, and the signs that a promising team will struggle.

Ben shares what he looks for in co‑founder alignment, how to recognize mutual respect and trust, and why the ability to have productive disagreements may be the single most important trait.

Ben also breaks down what “founder material” really means:

The episode then moves to assembling high-performing teams in deep tech.

Ben also talks candidly about the emotional burden founders carry, why being a solo founder is so demanding and then shares his views on how culture is shaped in those ventures.

Finally, scientists considering being founders will hear from Ben some concrete takeaways to support their journeys.

In this debut episode of ''Skills'', Julien sits with Dan Brunner, ex‑CTO and co‑founder of Commonwealth Fusion Systems (CFS), about the people side of building a fusion company.

CFS spun out of MIT, raised nearly 3B USD in venture capital, scaled to 1,000+ people and is now building SPARC, an experiment to demonstrate net fusion energy.

Dan built and led the team that designed SPARC and helped create the organizational foundations for one of the world’s most advanced fusion efforts.

In this conversation, Dan and Julien discuss:

-Dan’s path from fusion research to leading a world‑class engineering organization

-Moving from being an expert to leading experts

-How CFS approached “good hiring” in deep tech

-The challenge of integrating three cultures

-Building culture intentionally

-Communicating fusion to investors, customers and non‑experts

-“Getting out of the lab” to engage with investors and customers and understanding where fusion makes sense

Dan also reflects on:

-How he taught himself to hire

-Letting go of the desire to understand everything in depth, and shifting focus to enabling others

-The emotional process of deciding to step away as a co‑founder and trusting the team to carry the mission forward

Finally, he shares advice for the next generation of deep tech founders

If you are a scientific founder, aspiring CTO or deep‑tech investor, this episode gives you practical perspectives on leadership, hiring and culture from inside one of the most ambitious deep tech companies of our time.