• Foundational theories of block designs, incomplete block designs, and their existence, structure, and classifications. These works establish existence results, construction methods, and partial balance characterizations that underpin later optimization and design-of-experiments frameworks [5], [7], [8], [18], [19], [20].

• Evolution of formal optimal design criteria and theorems shaping how experiments are planned, analyzed, and optimized, including D-optimal-like criteria, equivalence theorems, and general optimization directions for combinatorial designs [2], [3], [4], [9], [13].

• Engineering-centric optimization patterns that seek minimum-weight, efficient structural designs and shell/plate configurations, integrating multidisciplinary considerations; a thread from theoretical design to tangible structural performance under weight and material constraints [6], [9], [15], [17].

• Systematic construction and decomposition approaches to high-order design families, including elementary decomposition, and explicit construction of 4-designs and 5-designs, illustrating both modular assembly and combinatorial expansion of design resources [1], [10], [11].

• Multi-factor experimental design methodologies and rotatable designs underpin explorations of response surfaces and interactions, highlighting higher-dimensional and rotational symmetry considerations in experimental planning [3], [12], [16].