It's easy. Just click the "Manage My Pledge" button and add the price for any add ons you like, include any additional charges for shipping as well (There's a chart on the bottom of the page). Remember, all the add ons will be available in the Pledge Manager as well.
A few weeks after the project closes, you will be sent an invitation to our Pledge Manager. In it, you will pic you final choices for wood, designs, linings, etc. Don't worry, you have some time to decide. You will also be able to modify you pledge any way but down. All of the Add Ons will be available there as well.
Don't see the answer to your question? Ask the project creator directly.