Two precast concrete plants in the Landesberg area were planned for the interior fitting of the armaments bunker: on one hand, a works with the cover name, “Rudolf” belonging to the firm of Dyckerhoff & Widmann in Utting am Ammersee and on the other, the “Erich” project of the firm of Held & Francke in Friedheim, south-west of Landsberg.

The “Erich” works, which was named for Erich Wirth, the Senior Site Manager for the armaments bunker, was intended to manufacture precast concrete elements, such as girders, column and ceiling elements, as well as staircases, from concrete. In the production process the liquid concrete with reinforcements was compacted by vibration in moulds. The moulds used for this purpose were heated by means of heated water, with the result that the concrete cured more quickly. Once they were cured, the precast concrete elements could be loaded, transported and installed in the bunker. The concentration camp prisoners from the Kaufering X camp were used in various areas of the manufacturing process.