An enhanced version of the Linear Embedding via Green's Operators (LEGO) method is introduced to analyze complex 3-D metallic structures located inside a single electromagnetic (EM) brick. For the sake of computational efficiency and memory storage requirement the surface of the entire structure is divided into smaller sub-domains and over each pair of neighboring sub-domains is defined set of characteristic basis functions (CBFs). To compress the problem all CBFs which are associated with insignificant singular values are truncated. Various comparisons between the direct solution which solves Electric Field Integral Equation (EFIE) directly over the structure and LEGO approach using CBFs are shown to prove the concept