A method for forming a metallic structure having multiple layers includes providing a main tool having a main formation surface corresponding to a desired shape of a first layer of material. The method also includes depositing the first layer of material on the main formation surface using a cold-spray deposition technique. The method also includes positioning a secondary tool having a secondary formation surface in a portion of a first volume defined by a first surface of the first layer of material. The method also includes depositing a second layer of material on the secondary formation surface using the cold-spray deposition technique. The method also includes removing the secondary tool such that the first volume is positioned between the first layer of material and the second layer of material.