The physical custody of Bitcoin keys ultimately boils down to a materials problem: how to securely store the 12 or 24 words of a seed phrase, ensuring it survives fire, water, and accidental damage. Yoseyomo, a Valencian startup, responded by creating a titanium coin, where the words are encoded in binary using a punch. In episode 79 of Toque de Ingenio, Iñaki Zubeldia explains how they researched existing storage solutions, the design decisions they made, and how they financed the initial production through a pre-sale.
Guest: Iñaki Zubeldia, who was presented in the episode as the founder of Yoseyomo. Interview published: May 26, 2026. Episode: 79. Duration: 1 h 22 min.
In this episode:
- Why the metal supports available on the market failed the fire, acid, and crushing tests.
- How to encode 24 words onto a small coin without engraving a single letter.
- What role did pre-sales, mass production, and the community play in the launch?
The conversation takes place two years after the product’s launch, with the company undergoing a major capital expansion. Iñaki shows the coin and its packaging to the camera while explaining them.
Why does a seed phrase end up as a piece of metal?
Iñaki explains that when creating a wallet, the software provides 12 or 24 words, randomly selected from a standard list of 2,048 terms. These words, in their specific order, are the only essential thing: if the device breaks, you simply need to enter them on another one. It’s typical to write them down on paper, and that’s where the problems begin.
One of the cases being recounted is that of a client, an industrial welder from Bilbao, who bought cryptocurrencies in 2013. He kept the document containing the details within the wallet’s cold storage box and subsequently lost the box. According to Iñaki, the application showed a balance of 44 million euros in 2026, which he was unable to move.
The product’s origin lies in its YouTube channel, Cryptodemy. Following a very popular post, he recorded a video where he marked the words with a hammer and chisel on stainless steel discs. His partner, Álvaro, who lives in Bilbao, wrote to him on September 9th, suggesting they create a practical and attractive version. Seven days later, they had the design for the coin, and the development took eight months of remote work.
Iñaki describes it as something poetic: a technology as sophisticated as blockchain, ultimately being safeguarded within a simple, analog piece of metal. The object has no electronics or software; its value lies in its durability and its ease of concealment.
Studying what already exists: tests involving fire, acid, and pressing.
Iñaki comes from marketing, and he recounts that his first action was a market study. He discovered a job as a cypherpunk activist who had been destroying metal supports using fire, acid, and a hydraulic press: cards to scratch with a punch, small booklets with rails to insert letters, and tubes with engraved rings.
A small aluminum booklet was melting. Another, made of stainless steel, withstood the heat, but the sheets forming the rails began to buckle under the heat, and the letters jumped out, causing the order to be lost. The tubes bent due to pressure, and when attempting to open them, the rings scattered.
“Products that were designed to protect your initial investment did not achieve their intended purpose”.
Iñaki Zubeldia 41:49.
The lesson applicable to other projects is that the material does not guarantee functionality. Steel that resists fire can fail due to the geometry of the overall structure or due to loose components. In the product design and development It’s important to define the failure conditions before sketching. The analysis resulted in Yoseyomo’s two requirements: a product that is indestructible and extremely easy to conceal.
Encode 24 words in binary on a titanium coin.
The central decision was not to include lyrics. The list of 2,048 words is arranged alphabetically, meaning each word occupies a specific position, which is represented by a number. The coin has 24 lines of dots, one for each word, and each dot represents a value of 1, 2, 4, 8, 16, and so on, to cover the entire list. The total number of dots marked indicates the position of the word.
Iñaki gives an example: if the word is number 3, there is no dot with that value, but marking 1 and 2 produces the result. The list is public, and Yoseyomo’s website shows which dots to mark for each word. The wallet determines the order, which is preserved because each line corresponds to a position in the phrase.
This system has two key advantages that Iñaki highlights. The first is the size: because there’s no text involved, the currency remains small. The second is the language: the lists are available in Chinese or Japanese, and these users can use the product, while users who rely on Latin characters cannot. The design complements the functionality: a Japanese sound name, referencing Satoshi Nakamoto, and a dark, understated image, reflecting the fact that someone who manages their own funds doesn’t want to reveal what they hold.
Punch, template, and seals: the details that make the object functional.
The case opens like a perfume case and initially reveals the coin. Below, there are QR codes with instructions, a punch, and a white-on-black template designed for people with presbyopia. Iñaki explains that users had requested a larger device, and the template was the solution to avoid enlarging it.
“Why don’t we want to make it bigger? Because then it becomes much harder to hide”.
Iñaki Zubeldia 46:20.
The punch doesn’t require a hammer: it’s simply pressed, leaving a mark. The recommended procedure is to mark first with a marker, check for any errors, and then fix the marks in place.
Once finished, security seals cover the coins and perform four functions. They conceal the markings; they have side cuts that break the adhesive if someone tries to remove it; they feature a unique serial number that reveals a replaced sticker; and they contain an NFC chip. Using the free app, the user can save a label like “my father’s wallet,” without any sensitive data, to distinguish multiple coins without exposing any.
Iñaki insists that these finishes are what differentiate between two similar products. It’s an argument to test with users the full use of an object during the… (The sentence is incomplete in Spanish, so I’ve stopped at a logical point.) prototype: to open, read, highlight, review, and seal.
Sell before manufacturing: pre-sales, packages, and community.
Yoseyomo went to the market on May 1st, 2024, without having produced any goods beforehand. Iñaki had explained the process within the Cryptodemy community and had gathered a waiting list of 100 people. Through a live video stream, they made approximately €16,000 in 48 hours, offering reduced prices to those who paid in advance. This money enabled them to commission the initial bulk production.
Following the live broadcast, they conducted a poll with a rating of 9.5. In September, when the product was delivered, the reviews gave a rating of 4.9 out of 5, which Iñaki interprets as expectations being met.
Following that, there was a first capital increase to pay the manufacturer and validate the marketing efforts. The product also won a Red Dot design award, the first for a physical crypto product, according to Iñaki.
At the time of the interview, the company was in a new €500,000 funding round, with over €300,000 of that coming from within the region via an investment vehicle.
From object to service: digital inheritance and next steps
The next question that was raised was what happens to someone’s cryptocurrencies upon their death. This led to the creation of Inheritance, a service for managing posthumous messages, which in 2025 expanded to include any digital, financial, or emotional asset. It is activated through three methods: a registration linked to a will, regular emails with a phone call prior to action, and designated contacts, all with a death certificate.
As many users were taking the capsule from the service using a real object, the partners decided to manufacture it in titanium, with a QR code containing the registration number. Iñaki presented it as a prototype designed to be fire-resistant, intended to be delivered as a symbol of the legacy.
Among the plans mentioned are a white-label branding format for insurance companies and the Bitcoin Race – a city-based scavenger hunt with 24 challenges planned for the final quarter of 2026. These are projects that were announced during the interview, not finalized results.
What can another development team learn?
The Yoseyomo case offers four key lessons for anyone developing a niche physical product:
- Define the failure conditions before drawing. Fire, acid, and crushing were the tests used to differentiate between a useful support and a decorative one.
- Code instead of writing. Converting words into binary positions reduced size and eliminated language dependence.
- Addressing usability through accessories. A template and a punch – without a hammer – prevented an object from becoming larger, thereby ensuring it remained hidden.
- Financing the initial batch with the community. A pre-sale with a waiting list covered the manufacturing and validated demand before any investment was made.
This episode outlines the project’s status as of May 2026: the currency being sold, the inheritance service in operation, and the Bitcoin Race currently in preparation. The details mentioned may have changed since then.
At i-mas, we develop physical products that must fulfill a specific function using a particular material, process, and intended use, from initial research and exploration of alternatives through to the first production series. If you’re working on a niche product with specific requirements for strength or usability Tell us about your project..
To continue reading: From the prototype to the first units: the case of Citring One.
Source of article: Interview with Edgar Guerrero and Iñaki Zubeldia on Toque de Ingenio. The excerpts cited link to the minute of the conversation. The project recommendations are an editorial summary from i-mas.
