In one example, an adapter assembly for a system for cold working a portion of a metal layer of a metal/composite structure is provided. The portion being cold worked may surround a hole in a structure that includes the metal layer and a non-metal layer. In some examples, the adapter assembly includes a shim adapter housing including a face wall, having a first aperture that is larger than the hole, and a side wall, extending from the face wall. A cavity is at least partially delimited by the face wall and the side wall. The adapter assembly also includes a shim, dimensioned to fit within the cavity. The shim has a second aperture that is larger than the first aperture. Other embodiments may be described.