I help product teams stop guessing.
Hi, I'm Marcin Klimaszewski. Fifteen years in product and UX. The job is always the same: take a stuck idea and turn it into a decision you can trust, fast.
- 15years in product and UX
- 100+workshops across Europe, with startups, scale-ups, and teams inside companies you know
- 2ndat TechArena Sweden 2026, solo, against 90+ people, with this exact format
Based in Warsaw. The day runs in English, anywhere in Europe.
Where I come from
I spent three years as Head of UX at Sanoma Learning, then years running design sprints. I still love the sprint, but once a working prototype can exist by lunch, five days carries a lot of theater. So I kept the part that matters and pressed it into a day.
Three years. A team of 35, hired across five countries.
Startups, scale-ups, and corporates across Europe. The lesson: a week beats a quarter.
2nd
Entered solo against 90+, most of them in teams, with this exact method. I would not sell a format I had not bet on myself.
4
Ionian Technologies booked a private day. Four challenges tested, eight hours to a decision, and a user test that changed the product.
From a private day at Ionian Technologies
Building has gotten easier. Distribution is now the challenge. User engagement is the tough part nowadays. We learned a few things about our users and about what we are going to do next.
Spyros Tsoukalas, Founder, Ionian Technologies
Rated 4.6/5 Excellent on Trustpilot. Read reviews →
How I run a room
The facilitator is the difference between a room that ships and a room that argues. Four moves do most of the work.
I stay neutral.
A facilitator guides the process, not the content. I protect your idea and your decision, I don't sell my own. A room can feel when the person running it has a horse in the race.
I own the clock.
Every block is timeboxed and I hold it, kindly but firmly. Half the job is knowing what comes next, so the room never loses the thread or runs out of day.
Everyone works, then everyone shares.
People think on their own first, then bring it to the room. It is how the sprint kills groupthink: a quiet expert's idea lands on its merit, before the loudest voice can bend the room around it.
The day ends in a decision.
When a call is needed I command the room and keep it calm while I do. A workshop that ends in good energy and no decision is a party with sticky notes.
And I keep it fun, because energy is something you manage, not something you hope for. Rooms that laugh, ship.
If you want to build sth real in 6 hours, while meeting cool like-minded people – do it! It will be worth your time.
Tomek RusiłkoDigital Product Leader, Lunar LogicWhat I do
Rapid product discovery, problem-framing workshops, design sprints, and user testing. Product Build Day is the one-day version: build against a real challenge, test it with users, leave with a decision. Evidence before investment.
Three shapes. Free community evenings across Europe. One-day Pro training in Berlin at 690 EUR a seat for product managers and designers. A private Teams day from 7,900 EUR, run inside your company against your own backlog.
The honest limits
One day gets you a working prototype, real reactions, and a smart plan for real evidence. Reactions, not results, and I will say those exact words in the room.
Sometimes a day shows that an idea needs proper discovery first. When that happens, I say so out loud, to the person who paid me.
Nobody sells certainty. If you need to stop guessing, a day is enough to start.
Fifteen minutes tells you if this fits.
Book a free callNo pitch. If a build day is not the right room for you, I will say so.