• This post is based on the Spanish video available here.

Imagine you have a business partner.
Or maybe you and your partner are saving Bitcoin together for the long term.
Both of you trust each other… but neither of you wants the other person to be able to move the funds alone.

This is where a multisignature wallet becomes a powerful solution.

In this guide, we’ll go step by step through the process of creating a 3-of-4 multisig wallet using Nunchuk, designed specifically for shared custody between two parties.

We’ll use two phones running Nunchuk and four different signing keys.

The setup will be 3-of-4, meaning that three signatures out of the four available are required to approve a transaction.

The keys in this setup will be:

2 hot keys stored on the phones

2 hardware keys using Blockstream Jade devices

First, an Important Disclaimer

Multisig is a very powerful tool, but it’s not always the right solution.

For most people who are simply self-custodying their own Bitcoin, a 12-word seed combined with a strong passphrase is already a very robust setup.

In fact, many people have lost access to their Bitcoin because they created complex multisig setups without proper backups.

So if you are learning about multisig for the first time, my recommendation is simple:

Practice everything on Testnet first.

Testnet is the perfect environment to experiment, break things, and learn — without risking real sats.

What You Need for This Setup

For this example we will use:

Two smartphones with the Nunchuk app installed

Two hardware wallets (Jade and Jade Plus)

Two software keys stored in the phones

Some Testnet4 sats

Why Nunchuk?

Nunchuk is a Bitcoin wallet available on mobile and desktop.

It offers both free and paid features, including services like inheritance planning.
For this tutorial, we’ll only use the free version.

One interesting feature is what Nunchuk calls Group Wallets, which makes multisig coordination between participants much easier.

The app also simplifies PSBT sharing between signers.

Step 1 Switch to Testnet

Open Nunchuk on both phones.

Go to Settings and switch the network to Testnet.

Step 2 Next, create a Nunchuk account.
This helps coordinate group wallets and makes sharing partially signed transactions easier.

The process is simple:

Enter your email

Receive a temporary password

Change it after logging in

Repeat the same process on the second phone.

Now each participant has:

A Nunchuk account

The app configured on their device

Step 3 — Add the Signing Keys

Before creating the wallet, Nunchuk requires that you add the keys first.

On the iPhone, we will add:

One hot key

One Jade hardware wallet

To use a Jade in Testnet:

Load your seed first, then go to:

Device → Settings → Network → Testnet

To export the key for multisig:

Options → Wallet → Export Xpub → Multisig

Now repeat a similar process on the Android phone:

One hot key

One Jade Plus hardware wallet

At this point, we have four total signing keys.

Step 4 — Create the Multisig Wallet

Now we can finally create the wallet.

In Nunchuk:

Create New Wallet → Group Wallet

Inside the settings you define the multisig policy.

By default, Nunchuk suggests 2-of-3, but for this tutorial we will create a 3-of-4 setup.

Next, add the keys that will participate.

From the Android phone:

Add the software key

Add the Jade Plus

Display the Group Wallet QR code

Scan that QR code from the iPhone to import the keys.

Because both participants created Nunchuk accounts, the keys will automatically appear on both devices.

Finally, press Create Wallet.

Step 5 — Receiving Bitcoin

Now the wallet is ready.

Either participant can generate a receiving address.

For this tutorial I sent a few Testnet transactions so we could also demonstrate coin control, selecting specific UTXOs when spending.

Nunchuk also includes a chat feature inside group wallets, which helps coordinate between participants.

The Most Important part: Backup BSMS

This part is critical.

You must save the BSMS file.

BSMS stands for Bitcoin Secure Multisig Setup.

This file contains essential information about the wallet, including:

The wallet descriptor

The extended public keys (xpubs)

The multisig configuration

To restore a multisig wallet you need more than just the seeds.

You need:

The seeds of the signing keys

The BSMS file

Without this information, recovery becomes impossible.

Step 6 Sending a Transaction

To send funds:

Create a transaction

Select the UTXO manually (coin control)

Share the PSBT with the other participants

Collect the required signatures

Since this is a 3-of-4 setup, the transaction will only be finalized once three keys sign it.

In this demo, we signed the transaction from both phones to complete the process.

Final Thoughts

As you can see, creating a multisig wallet for shared custody using Nunchuk is surprisingly simple.

But remember:

Multisig security comes from good operational practices.

To recreate this setup you must keep:

The seed backups of each signing key

The BSMS file

And before moving real funds…

Test everything on Testnet.

Always.