Offering Mandala is Handmade Mandala. Mandala is in Tibetan Buddhism, Mandalas come in two varities it can represent the universe as it is used in the Mandala Offering Ritual, where one symbolically offers the entire universe. Several Rings can be placed on Top of each other filled with Rice and Precious Objects. During the Offering one Recites Mandala Offering Prayers. In the center of the mandala is Mount Meru, the central axis in the Buddhist Cosmos.
The best known mandalas are part of the world of Tantra they represent the "3D Palace" of a specific Meditation Buddha or deity. In the Tibetan Tradition, they come as thangkas (scroll-paintings), wall paintings, sand-drawings and 3D models of e.g. wood or metal. A mandala can be "read" and studied like a text and most important be used for tantric meditation. The purpose of a mandala is to acquaint the student with the tantra, and thus allowing the student to identify with the deity and its sacred surroundings as the mandala.