Sandwich panels consisting of a foamed metal core and two metal face sheets can be fairly easily obtained by bonding the face sheets to a piece of foam with adhesives. Alternatively, if pure metallic bonding is required, conventional sheets of metal—aluminum or steel—are roll-clad to a sheet of foamable precursor material. The resulting composite can be deformed in an optional step, e.g., deep drawing. The final heat treatment, in which only the foamable core expands and the face sheets remain dense, then leads to sandwich structures such as the one shown in Figure 5b. Aluminum foam can be combined with steel or titanium face sheets as well as with aluminum face sheets. In the latter case, alloys with melting points that are different from the core material and the face sheets must be used to avoid melting the face sheets during foaming. A large aluminum/aluminum foam sandwich was developed in a joint effort by the German car maker Karmann in Osnabrck and Fraunhofer-Institute in Bremen for a concept car in which structural aluminum foam applications were demonstrated. Such sandwiches are three-dimensional, up to two meters long and about one meter wide.