Abstract: A process and device for manufacturing a composite building panel of the type comprising a facing layer made from a plurality of facing elements, such as brick slices or stone slices for example, retained in a spaced apart relationship, and a magnetically attractible particulate material disposed between the facing elements to imitate mortar. A rigid backing layer is provided, spaced from the spacing layer, the space between the facing and backing layers being filled with an insulation/bonding layer. The device for use in manufacturing the building panel comprises a facing element holder in the form of a structure with a plurality of recesses for receiving therein facing elements, also including spacers between recesses in order to maintain the facing elements in a spaced apart relationship. Ceramic magnets are provided on the spacers for retaining temporarily thereto the particulate material against gravity, until the insulation/bonding layer is built which retains all the elements of the panel together.