Unicorn allows for the creation of multiple carts, each of which can target multiple markets.
A cart can be created from by click the 'Create cart' button on the cart index page. The first Cart you build will be set as the 'Default' Cart.
You will then be directed to fill in the name and select the target markets before clicking the 'Save' button.
Once the cart has been saved you will directed to the cart building page with the default blocks already created.
Hint: If you have the same Rewards and Shipping Threshold for each Market, you can select all your Markets for your Default Cart.