This case study documents how ProtoBag Studio developed a custom modular carry tool with a Bonn-based educator — from a first email in German to a second approved prototype five months later. The client preferred anonymity, so product details, dimensions, and design files are held under NDA. The case study below is published with that preference respected.
The client is a Sonderpädagogin (special-education teacher) from Bonn, Germany. She was a first-time founder developing a teaching tool for use in a specialised school setting. She had no factory contacts, no tech pack, and no design background — but she had a clear idea of what the product needed to do and the patience to iterate.
Our first reply was not a quote — it was five structured questions about how the modular structure attaches, whether the tool needs to fold flat, durability priorities, colourway flexibility, and expected lifespan. Each answer would change the structure, materials, and feasibility. Without them, any quote would be a guess.
The first prototype was completed in October 2025. After four weeks of structured feedback tracked in a shared Google Sheet, the second prototype was completed in January 2026. The client wrote: "Ich bin sehr zufrieden mit dem Ergebnis. Es sind viele sehr schöne Details umgesetzt worden."
What made this consultation-first project work: German throughout (zero translation friction), small batch sampling-led approach, honest constraints flagged early, and a 4-column shared sheet for tracking revisions. These are small things, but on small projects with high attention to detail, the small things determine whether the project is enjoyable or stressful for both sides.
If your project sounds similar — a first or second physical product for a specialised audience, without a polished tech pack but with a clear idea, best discussed in German, English, or Chinese — get in touch via the contact form. The first reply will be questions, not a quote. See also our guide on finding a custom bag manufacturer in Europe and our 8-step sampling and production process.