A sandwich structure includes two face plates, with a lattice structure between the plates, and with hard points at selected locations. The face plates, and the lattice structure with its hard points, may all be made as a single continuous piece by an additive manufacturing process. The hard points may be strengthened and/or stiffened areas of the lattice that may be used for connecting fasteners, or for other purposes. The hard points may be located at the junction between the lattice and one of the faces, and may be a locally thickened portion on one of the faces, for example being a cylindrical or parallelepiped protrusion out from the face. The hard points may serve the purpose of a built-in nut plate, such as themselves containing threaded holes, or by having a threaded inserts put into holes or recesses in the hard points.