Methods and apparatus for forming a housing, such as for an electronic device, from multi-layer materials are disclosed. The multi-layer materials include at least two layers. Typically, one or more of the layers are metal. However, different layers of the multi-layer materials can be different metals. In one embodiment, an inner layer of the multi-layer materials can be provided with or form internal features that can be for attaching parts or components to the multi-layer materials. In another embodiment, processing of an inner layer of the multi-layer materials can facilitate part formation with increased curvature and/or internal part clearance. In another embodiment, the multi-layer materials can include an intermediate layer that facilitates creation of internal features that can be for attaching parts or components to the multi-layer materials. In still another embodiment, the multi-layer materials can provide a protective layer that serves to protect an outer surface of the housing during manufacturing and/or assembly.