A Kingdom in a Box

You bought an old wooden box for storage. When the things you put inside start disappearing, you discover the box is connected to a dying kingdom in another world. They need food, clean water, medicine, tools and knowledge. You have access to the modern world. They have gold, silver, gems and resources to trade. Even stranger, a mysterious dial lets you control the size of anything you send. What starts with a few supplies could change an entire civilization.