First part: Sending funds

  1. Download Electrum wallet
  2. Follow these steps:

3. Create 3/2 wallet

4. Carefully write down and save your seed

5. Add cosigner 2 and cosigner 3 keys one by one

In the end all 3 parties of the deal should have the same set of wallet addresses

6. In Electrum go to Tools - Plugins and activate "Cosigner Pool" plugin

7. Transfer BTC to any of your multisig addresses (Hint: to show wallet addresses tab simply go to Wallet - Addresses in Electrum. Addresses tab should appear).

Note that address should start from number 3 and [2of3] label should be shown in the header of the wallet

After 3 parties confirm that funds are received, Seller sends item to a Buyer directly.

First part of deal is done.

Second part: Receiving funds

After buyer confirms receiving of an item he sends Warrantor and Seller a message about finishing a deal, parties sign a funds withdrawal from multisig wallet to seller's wallet.

The deal is officially done.