Four ways to build a cold wallet

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True cold storage means your private keys are created and kept on something that never touches the internet, and are never typed, photographed or saved to the cloud. You can get there for nothing, or spend several hundred dollars for more protection. Here are four complete builds. Each one has a shopping list and step-by-step checklist on the cold wallet kits page.

At a glance

Kit	Cost	Time	Coins	How cold
Quick	$0–15	~1 hour	Any	Radios off, not removed
Minimum (SeedSigner)	~$50–70	~2 hours	Bitcoin	No radios at all
Air-gapped laptop	~$200–280	Half a day	Any	Radios physically removed
Best of the best (2-of-3 multisig)	~$600–750	A weekend	Bitcoin	Three devices, three places

Prices are approximate as of November 2026.

1. Quick: running tonight

What it is: a spare laptop you already own, booted from a Tails USB stick with no network, running Sparrow Wallet. Your normal computer keeps a watch-only copy and broadcasts transactions.

Who it’s for: anyone learning. Run the whole process on signet first, with free test coins.

Weakness: the Wi-Fi and Bluetooth hardware is still inside the machine, just switched off. It’s “mostly cold.” Good for learning, not for serious savings.

Full walkthrough: Cold storage without a hardware wallet.

2. Minimum: SeedSigner

What it is: SeedSigner, an open-source signer you build from a Raspberry Pi Zero v1.3 (the version with no Wi-Fi chip), a small screen and a camera. It has no radios, no storage, and forgets everything when unplugged. Transactions move by QR code.

Who it’s for: Bitcoin holders who want truly cold storage at the lowest price.

Trade-off: it doesn’t store your seed. You scan your seed, saved as a SeedQR card, each time you sign. That’s a security feature, and it means guarding the SeedQR card as carefully as the words.

Full walkthrough: Build a SeedSigner.

3. Air-gapped laptop

What it is: a used ThinkPad T480 or similar, about $150–250, with the Wi-Fi/Bluetooth card unscrewed and removed, running Tails. Used for nothing else, ever.

Who it’s for: people holding coins other than Bitcoin, or anyone who wants a full screen and keyboard to check transactions on.

Trade-off: more steps, more chances for a mistake. Moving files by USB stick carries a small malware risk; signing by QR code with the webcam avoids it.

Full walkthrough: Choosing and preparing an air-gapped laptop.

4. Best of the best: 2-of-3 multisig

What it is: three signing devices from three different makers, for example a Coldcard Q, a Keystone 3 Pro and your SeedSigner. Each holds one key. Any two can approve a spend. Keys and backups are stored in three different places.

Who it’s for: anyone for whom a total loss would be life-changing.

Why it’s worth the effort: one lost device, one stolen backup, or one flawed device can’t take your funds. It’s also the best inheritance tool available.

Full walkthrough: 2-of-3 multisig.

Rules for every kit

1. Buy hardware only from the maker’s own site. Never a reseller, never a device with a seed already in the box.
2. Make the seed on the device, ideally with dice for extra randomness.
3. Back up on steel once real money is involved. Paper burns. See Seed backups.
4. Test recovery before funding. Send a little, wipe, restore, and confirm the same addresses come back.
5. Verify every receive address on the cold device’s screen, not just on your computer.
6. Plan for someone else to recover it. See Inheritance planning.

Which should you pick?

• Learning right now: Quick, on signet. Tonight.
• Bitcoin, small to medium amount: Minimum. It also becomes your third key if you move up to multisig, so nothing is wasted.
• Other coins too: Air-gapped laptop.
• Life-changing amount: Best of the best.

Ready? Open the cold wallet kits checklist and start ticking.