In stoichiometric compounds (compounds with fixed ratios of elements), the elemental ratios are dictated by chemical stability, which constrains how much the composition, and consequently the number of valence electron-per-atom (e/a) ratio, can be adjusted. Tuning e/a has proved to be a promising strategy to architect magnetic properties in many intermetallic compounds, especially those with complex structures including quasicrystals (QCs) and their structurally related approximant crystals (ACs).