Abstract: A bulk absorber has a continuous concentration gradient of particles with dielectric or magnetic altered properties. The bulk absorber may be made from foam or, ceramic. The particles may be carbon fibers, carbon black, carbon whiskers, coated hollow microspheres, or a combination thereof. A manufacturing system for fabricating a bulk absorber has two delivery devices, a controller, an intermingling device, a positioning device, and a forming device. The delivery devices produce flows of absorber precursors, with at least one of the flows having a concentration of particles having dielectric or magnetic altering properties. The ratio of the flows is controlled by the controller. The intermingling device receives and mixes the flows to produce a combined flow. The particle concentration in the combined flow is controlled by the controller. The positioning device directs the depositing of the combined flow into a cavity to build a non-solidified item.