A sandwich panel is any structure made of three layers: a low-density core, and a thin skin-layer bonded to each side. What is ACP (Aluminium Composite Panel)?. ACP may refer to: Contents. Aluminium composite panel is popularly known as ACP. ACP is called aluminum composite panel as a new type of decorative materials with its optional color diversity, convenient construction method, excellent. Items 1 - 8 of 273 · Aluminium Composite Panel or ACP sheet is used for building exteriors, interior applications, and signage.