A shell and core structure is a layered design in which one material forms an outer layer around a different inner material. In manufacturing, the shell can provide shape, protection, insulation, or surface finish, while the core supplies strength, flexibility, conductivity, or another functional property. In additive manufacturing, this is often created by coordinating two feeds so the materials stay aligned and continuous.
In cyber security, shell-and-core designs matter in hardware and physical defenses because the outer layer may hide or protect sensitive inner components. They can appear in tamper-resistant enclosures, cables, sensors, and embedded devices where the shell helps resist probing, moisture, or mechanical damage. Security teams care about them because poor bonding, uneven thickness, or misalignment can create weak points that affect reliability, inspection, or tamper evidence. The concept also appears in secure manufacturing, where consistent layering helps ensure devices are built as intended.