Prototyping and Validation Grant: Stealth Startup

Why Slowing Down to Find the Right Co-Founder Is Actually the Fastest Path.

What they did before building anything is the part worth copying.

Before Melany Macías and Katerina Tchilinguirov agreed to build anything together, they gave themselves three weeks to find out if they could actually work together.

Everything that came after rested on it.

They came from different cohorts of the Aalto Founder Sprint. Melany did Fall '25. Katerina did Spring '26. Their first official crossing was at Junction, one of Europe's largest hackathons, and they worked together for a weekend to win 1st place in the Wolt challenge.

Melany was one of two women in the Founder Sprint cohort F25. The room, she says, was different from any she'd been in. "I had never been surrounded by people who just wanted to go into execution. This was the first time I was surrounded by ambitious doers, and it pushed me to leave my engineering box to become a hypergeneralist.”

Katerina saw it from the outside. "She seemed insanely decisive," she says. "Asking things like: what are the most outdated, underserved industries? Name raising startups or incumbents and what their approach is. What are their competitors like? Really tactical questions, rapid fire."

By the end of the hackathon, Katerina asked Melany if she wanted to be co-founders.

Melany said no.

Months later, Katerina called. Her situation had changed and she needed a co-founder.

"I was watching a movie and she called me and said: can we trial?" Melany recalls.

They gave themselves three weeks. 

The Credibility

Melany spent some time in Silicon Valley and worked at a venture firm, where she evaluated hundreds of companies and founders. She came back to Finland, as Katerina jokes, "more delusional than ever"  seeing patterns and opportunities.

Katerina's path was different but equally rigorous. She worked in consulting, advised startups on their pitch decks, and built fundraising decks for CVS, a Fortune 500 company. She was part of the Crew at Founders House Helsinki.

The Moment

Melany came in with doubts. They'd worked together once, for a weekend, and she wasn't sure it would translate to building something real.

One week in, they were walking through the city when Katerina spotted a business, walked in with zero preparation, introduced herself to the person inside, and started pitching on the spot.

"I would have never done that," Melany says. "We hadn't prepared, but she just went with it. And I thought: none of us have worked at sales before, but we're going to figure it out together."

A weekend was enough to want to try. Three weeks answered something harder: whether the way each of them worked under pressure was the thing the other was missing.

"I start overengineering sometimes, and she pulls me back: who requested this feature? We should be calling customers," Melany says. "And when I see her spending too long on a one-pager, I ask: who are we sending this to? Does it need to be so polished?"

"Two people can be highly respectable, efficient, and passionate. But when they work together, that may not translate," Katerina says. "Compatible co-founders multiply each other, not just add to each other. That’s a hire.” Melany added, “It should never feel like you are in a competition with your co-founder."

Built at Aalto

Both founders came through the Aalto Founder Sprint, the flagship programme of Aalto Founder School. Aalto University ranks first in Finland and is the birthplace of 30% of Finnish unicorns.

"Whatever ambition and agency they had when joining is now an order of magnitude greater," Mårten Mickos said at Katerina's cohorts’ graduation.

These are two founders who came through one of the most demanding founder programmes in the Nordics, tested their partnership before committing to it, and got to customers with institutional backing from Aalto behind them.

What They'd Tell Students

"I couldn't bring myself to enjoy working with someone else, even though there were multiple insanely talented people," Melany says.

She pauses.

"But with the right cofounder, it's also so fun: we're always laughing. And of course, you should pick someone you can trust blindly, because I mean, it's 50% of your company. Are they worth sharing your exit with?” 

“The best way to figure out if you work well with someone is a fast-paced hackathon. Everyone can carve out time for a quick hackathon" Katerina says.

She adds: "Have the audacity to aim beyond the ‘best-case scenario’. And when priorities change—as they always do—be willing to strip away ego and reasses priorities every morning, hour, and minute. Our time is so limited."