The invention relates to a set for creating a process reactor for forming metallic layers on at least one substrate, the layers being formed by the precipitation of metal ions contained in a fluid onto the substrates. Said set essentially comprises the following structural elements: a reactor housing (3) comprising two ends (4, 5), a fluid flowing through the reactor housing from one end to the other; a device (6) which is arranged in the region of the efflux (4) from the reactor housing (3) and is used to receive the substrate; at least one overflow (8) which is arranged in the region of the efflux (4) from the reactor housing (3) and via which the fluid (F) flowing in the direction of the substrate (2) can flow out of the reactor housing (3); a collecting tank (10) for receiving the fluid (F) flowing out via the overflow (8); means for redirecting the collected fluid into the reactor housing (3); and at least one anode. In order to obtain a largely homogeneous coating, the process reactor also optionally comprises at least one of the following structural elements: at least one flow adjusting device (S) for the targeted control of the fluid (F) inside the reactor housing (3); at least one field adjusting device (E) for the targeted control of the electrical field created inside the reactor housing (3); at least one auxiliary electrode (H) that can receive either a positive or negative potential and is arranged between the substrate (2) to be coated and the opposite end (5) of the reactor housing (3); at least one diaphragm (B) for orienting the electrical field created inside the reactor hosuing (3); at least one diaphragm (B) for orienting the flow of the fluid (F) inside the reactor housing (3); and at least one ring element (R) for reducing the inner diameter (3i) of the reactor housing (3).