Indoor 4 or 6 inch Planters with Optimal Drainage 3D Printed Planters provide great aeration for plants when planted directly into. The Unique material is made from Corn, Beets and Wheat Grass. It's encouraged to plant directly into these planters, as they balance the nitrogen in the soil! Lightweight and Durable, these planters are 100% recyclable, biodegradable and compostable.