The present invention relates to methods of forming voids in concrete elements, and to a void former apparatus and system useful for this application. The void former unit comprises a first void former element comprising a first surface and a first opening in the first surface and a second void former element comprising a second surface and a second opening in the second surface, wherein the first void former element and the second void former element detachably connect to form a passage between the first opening and the second opening, and a void space between the first surface and the second surface surrounding the passage. Multiple void former units can detachably connect to form a void former system comprising a single continuous void space. While exemplified by use in concrete elements, other uses of the void former unit and void former system are envisaged.