Build It Yourself

In Choosing a Wallet, we mentioned SeedSigner as a hardware option for cold storage. It deserves its own guide, because it takes a different approach: you build it yourself, it stores nothing, and it's air-gapped by design.

1. What SeedSigner Is

SeedSigner is a free, open-source (MIT-licensed), Bitcoin-only signing device that you assemble from inexpensive, off-the-shelf parts (a Raspberry Pi Zero, a small screen, and a camera) for under $50. The project's goal is to lower the cost and complexity of secure Bitcoin self-custody, and especially of multisig.

The software is free; you supply the hardware. And like the other devices we cover, SeedSigner is a signer: it holds and signs with your keys, while a coordinator wallet (such as Sparrow) watches your balance and builds transactions.

2. Two Big Ideas: Stateless and Air-Gapped

Two design choices set SeedSigner apart:

• Stateless. It never stores your keys. You load (or generate) your recovery phrase at the start of a session; it lives only in memory, and the moment you remove power, it's wiped. There is nothing on the device to steal. A powered-down SeedSigner is just a Raspberry Pi.
• Air-gapped. The recommended Pi Zero has no WiFi and no Bluetooth, and the device never connects to a computer for data. It reads your unsigned transaction by scanning a QR code with its camera, and shows the signed transaction as a QR code on its screen. It draws power from a simple power bank: power only, never a data cable to a computer.

3. Why Build It Yourself?

Assembling your own signer sounds intimidating, but it's a real security advantage:

• No supply-chain trust. A device you build from generic, non-descript parts can't be tampered with in transit the way a sealed retail unit theoretically could.
• Verifiable software. The code is fully open-source with reproducible builds, so you can confirm exactly what's running on the device.
• Low cost, no excuses. At under $50, proper cold storage, and multisig, is within reach for everyone.

Assembly needs no soldering: the parts simply connect together, and you flash the software onto a microSD card.

4. Security and Features

• Your own randomness. Generate a seed from dice rolls or camera entropy, so you don't have to trust the device's randomness.
• BIP39 passphrases for hidden wallets.
• SeedQR backups: store your recovery phrase as a compact QR code you can scan back in.
• Single-sig and multisig, with support for modern script types including Taproot.
• PSBT review and signing. You confirm every detail on the device's own screen.

5. Bitcoin-Only and Open

SeedSigner does one thing: secure your Bitcoin. It's MIT-licensed free software with reproducible builds, developed in the open by a community of contributors, so you never have to take a company's word for what it does.

6. It Works With Your Software

SeedSigner pairs with any coordinator that speaks QR, including Sparrow on the desktop. Transactions move back and forth as scannable QR codes (standard PSBT), and the device handles both single-sig and multisig. See Choosing a Wallet for coordinator options.

7. Is SeedSigner Right for You?

SeedSigner is the most hands-on option we cover. You assemble it yourself and there's a learning curve, but it's the cheapest path into serious cold storage, and a long-time favourite for multisig. Because it's stateless, your seed backup is everything: there's no device to fall back on, so that metal backup matters more than ever. If you'd rather have a polished, ready-made device, see our Coldcard guide. If you want maximum DIY, low cost, and verifiability, SeedSigner is hard to beat.

8. What You'll Need

• A Raspberry Pi Zero 1.3, the version with no WiFi or Bluetooth.
• A Waveshare 1.3-inch LCD (240×240) and a compatible Pi camera.
• An enclosure: 3D-print the open-source design or buy one.
• A microSD card to flash the software, and a power bank for power.
• A coordinator wallet (such as Sparrow) and a metal backup plate.

9. Building and Setting It Up (The High-Level Path)

This is the shape of the process. For the exact parts list and click-by-click, follow SeedSigner's own documentation, linked at the bottom.

• Source the parts and 3D-print or buy the case.
• Download the software from the official source only, the SeedSigner releases page, and verify it before flashing it to the microSD card.
• Assemble the device (no soldering required) and power it from a power bank.
• Generate your seed with dice or camera entropy (or load an existing one). Write the recovery words on paper, then metal. Never as a digital file, screenshot, or photo.
• Optionally add a passphrase, and create a SeedQR backup if you want one.
• Pair it with your coordinator (Sparrow) by scanning QR codes back and forth. No cables involved.
• Receive a small test amount first, verify the address on the SeedSigner screen, and do a recovery dry run before trusting it with serious money.

10. The Golden Rules of Self-Custody

• Your recovery words are the keys. Never type them into a website, app, or "support agent" chat. No legitimate person or wallet will ever ask.
• Keep them offline. No photos, no cloud, no password managers, no email. Metal backup, stored privately.
• Verify addresses on the device. Always confirm a receive address on the SeedSigner's own screen.
• Source parts and software from official places, and start with a small test amount before moving real savings.
• Beware impersonators. Scammers pose as wallet "support" on Telegram, X, and Discord. Limestone City Bitcoin will never DM you first or ask for your recovery phrase.

Limestone City Bitcoin is not affiliated with the SeedSigner project. This guide is educational and is not financial advice.