This paper proposes that the regular tetrahedron serves as a universal design principle connecting quantum information theory, structural engineering, quantum biology, network topology, theological geometry, electrical engineering, psycho-social architecture, and financial systems. The framework demonstrates that the geometric properties of the tetrahedron; specifically its equiangularity, isostatic rigidity, and informational completeness; manifest as a recurring structural signature across scales from subatomic measurement to macroscopic network architecture and ontological frameworks. In quantum information theory, Symmetric Informationally Complete Positive Operator-Valued Measures (SIC-POVMs) arrange four measurement vectors as a regular tetrahedron inscribed in the Bloch sphere, satisfying the equiangular overlap condition |⟨ψⱼ|ψₖ⟩|² = 1/(d+1) = 1/3. This geometry enables full quantum state tomography from a single measurement basis, eliminating the sifting inefficiency and reference frame dependence of orthogonal protocols such as BB84. In structural engineering, Maxwell's rigidity criterion (E ≥ 3V − 6) identifies the tetrahedron (V=4, E=6) as the minimum isostatically rigid three-dimensional structure; the simplest geometry that encloses volume and resists deformation without internal bracing. In quantum biology, Fisher's Posner molecule hypothesis identifies calcium phosphate clusters (Ca₉(PO₄)₆) as potential carriers of quantum coherence in neural systems. The phosphate group PO₄ is itself a regular tetrahedron, with the tetrahedral bond angle satisfying cos(109.47°) = −1/3; the same constant governing SIC-POVM overlap. In network topology, Ollivier-Ricci curvature analysis distinguishes fragile hub-and-spoke architectures (negative curvature) from resilient mesh topologies (positive curvature), where triangulated connectivity provides redundant pathways resistant to single-node failure. In theological topology, the medieval Scutum Fidei (Shield of the Trinity) physically maps to the complete graph K₄. This tetrahedral geometry provides the absolute minimum vertices and edges required to resolve the Athanasian constraint of Trinitarian co-equality; maintaining distinction among three entities while constituting a singular, indivisible essence; without collapsing into planar, structurally deficient reductions such as Modalism or Partialism. In electrical engineering, the framework identifies the "floating neutral" as a catastrophic failure mode in Wye (star) topologies where a centralized reference point is severed. The Protocol mathematically defines the Wye-to-Delta transformation; shifting from centralized fragility to distributed, isostatic mesh resilience; as the universal intervention for restoring system equilibrium. In psycho-social architecture, the framework models the neurodivergent identity (the Geodesic Self) and family structures as tetrahedral volumes (K₄). It reframes systemic failures, such as executive dysfunction or high-conflict divorce, as "floating neutral" events, resolvable only through a phase transition to distributed, sovereign interdependence. In financial topology, the framework applies these geometric principles to market mechanics, contrasting the fragile, centralized Wye topology of beneficial ownership (e.g., the DTCC) with the resilient, Delta-mesh topology of Direct Registration Systems (DRS), where participants perform distributed market tomography to detect structural manipulation. This framework is presented as a defensive publication establishing prior art in the public domain. The author is an independent researcher with 16 years of experience in civilian DoD electrical engineering, specializing in three-phase power distribution and motor system topology. Applications to assistive technology design for neurodivergent communication systems are discussed.