The gap
Self-custody hardware is built for holding, not spending. Signing takes tens of seconds and assumes you are at a desk moving funds on purpose, not halfway through a round.
Motonari Wallet
Cold storage,
built for play.
A USB-C hardware wallet for in-game crypto on Solana and Ethereum. Keys were made inside a secure element and never came out. Not for the game, not for the driver, not for you.
MOTONARIETH
0.0042 ETH
to 0x7fA9…3C1b
HOLD TO CONFIRM
The opportunity
Games moved money
before they moved custody.
In-game economies already move real value. Custody never followed them. Assets sit in exchange accounts and hot wallets on the same machine that runs mods, overlays and anti-cheat drivers. General-purpose hardware wallets are built for rare, high-value transfers. A $0.40 purchase mid-match is the opposite case.
What we built
A USB-C device that turns a signature into a three-second physical action, with keys generated inside a secure element that never exports them. Seven board revisions, each one bench-validated.
Where it stopped
The final revision met spec in 2024. The four co-founders paid for every board out of their own pockets, and that money ran out before tooling and certification. Research and prototyping stopped there and the device never reached market.
The device
Small enough to forget.
Strict enough to trust.
It lives on a desk beside a keyboard, not in a safe. Every decision in the industrial design and the interface follows from that.
Plug in and go
Bus-powered over USB-C and class-compliant, so it enumerates without a driver install, a pairing code or an account.
One button and a small screen
The entire user interface. No menu tree, no companion app, no configuration state to get wrong.
No battery, no radio
No cell to degrade and no wireless attack surface. The USB-C connector is the only ingress and egress path on the device.
Security
Your keys never leave.
Not even for you.
Software key storage asks you to trust the machine an attacker already owns. Motonari moved the key behind a hardware boundary the host cannot cross, then made physical recovery of that key destructive.
-
01
Sealed at birth
Key material is generated inside the secure element and has no export path. No seed file, no backup blob, nothing on the host to exfiltrate.
-
02
Nothing signs itself
Signing is gated on a physical press. An attacker with full control of the host can issue requests indefinitely and collect nothing.
-
03
You see the real number
Amount and destination are rendered on the device display, outside the compromised trust domain. What you approve is what gets signed.
-
04
Hard to open, harder to read
The secure element is routed on an inner layer between reference planes. Landing a probe on those nets means milling through the board first.
The flow
Three steps, under four seconds.
- 01
Plug in
Connect over USB-C. The device enumerates and the title sees an available signer.
- 02
Read the screen
The title submits a transaction for approval. Amount and destination render on the device display.
- 03
Press to sign
Hold to confirm. The signature returns over the same link and the purchase settles.
Networks
Solana and Ethereum.
-
SOL
Solana
Settlement cost low enough that a $0.40 purchase is not absurd, with confirmation latency short enough to clear inside a match.
-
ETH
Ethereum
Where the assets and wallets players already held actually lived, so a gaming signer had to support both chains rather than pick one.
Research and development
Seven boards.
One constraint that drove all of them.
Putting the secure element where a probe cannot reach it is a placement and stack-up decision, not a firmware one. It has to be made before the first trace is routed, and it constrains everything downstream. Two years of development came out of holding that line.
- AArchitecture
- BStack-up
- CBring-up
- DSignal integrity
- EPower integrity
- FEMC
- GTo spec
Architecture and trust partitioning
The host controller and the secure element sit on opposite sides of a deliberate trust boundary. The STM32 owns the display, the button and the USB stack. It can request a signature and it can never read a key. Drawing that line first is what makes the rest of the design defensible.
Stack-up and signal integrity
A four-layer stack-up with the secure element routed on an inner layer between reference planes. The USB high-speed pair is length-matched and impedance-controlled to the 90 ohm differential target, with an unbroken return path beneath it. Split a reference plane under that pair and you get intermittent enumeration that no amount of firmware will fix.
Power integrity and EMC
Isolated rails and local decoupling so switching transients on the digital side never couple into the secure domain. Radiated emissions were scanned on a spectrum analyser between spins and corrected in layout rather than buried under filtering, because filtering a layout problem adds cost to every unit ever built.
Bring-up and design iteration
Every revision went through the same loop: power sequencing, rail margining, enumeration, then signal capture on the scope against the datasheet limits. Findings fed the next spin. Seven boards is what it took to close every one of those observations rather than document them as known issues.
Tech specs
As it was built.
- Key storage
- Dedicated secure element. Keys are generated on-device and never exported
- Host controller
- STM32, ARM Cortex-M
- Networks
- Solana, Ethereum
- Interface
- USB-C. No radio, no battery
- PCB
- 4-layer FR-4; secure-element routing on inner layers between ground planes
- Signal integrity
- Length-matched, shielded USB differential pair; isolated power rails
- Confirmation
- On-device display plus physical confirm button; no signature without a press
- Funding
- Self-funded by the four co-founders. No outside capital was ever raised
- Production status
- Prototype only. Never manufactured at volume and never sold
Questions
The short answers.
What was Motonari Studio?
A hardware company founded in Austin, Texas in October 2022 by four co-founders. It designed a USB-C cold-storage wallet for in-game cryptocurrency payments on Solana and Ethereum, built around an STM32 microcontroller and a dedicated secure element on a four-layer board.
How was the work funded?
By the four co-founders, out of their own money. Motonari never raised outside capital. Every one of the seven board revisions, along with the parts, tooling and lab time behind them, was paid for by the founders.
What happened to the company?
Research and prototyping ended in October 2024 when the founders' own funding ran out. The final board revision met spec on the bench, but the project never reached tooling, certification or a production run. The device never reached market.
Can I buy one?
No. The device was a working prototype that was never manufactured at volume and never sold. There is no storefront, no firmware download and no support. Anything claiming to sell one is not connected to this project.
Which networks did it support?
Solana and Ethereum. Solana kept fees low enough for a sub-dollar in-game purchase to make sense. Ethereum was where the assets players already held actually lived.
What made it different from a normal hardware wallet?
The use case. General-purpose wallets are built for infrequent, high-value transfers. Motonari was built for frequent, low-value signing that happens mid-game, on a machine running mods, overlays and anti-cheat drivers, so the design started by assuming the PC was hostile.
Is this site an archive?
Yes. Motonari Studio is discontinued and this site is a record of what was designed and built between 2022 and 2024. Nothing here is for sale, in production or supported.
Record
Seven revisions.
No production run.
Motonari Studio ran from October 2022 to October 2024 in Austin, Texas. Four co-founders paid for the work themselves and never raised outside capital. The board reached spec on the bench. It never reached tooling, certification or a factory, and no unit was ever sold.
Archived record. Nothing on this site is for sale and no product is supported.