The T module recursively self-fills with tau-scaled versions of itself, in complement with a stop-gap or "unfinished business" mod called the Remainder Tet or R module, shown in orange.
Keep filling the R mod with smaller T mods if you like, but expect smaller terminal R mods.
Phi-scaled Ts and Rs together make a cube, other shapes.
Plus if you regard a golden cuboid (1 x phi x tau (tau = 1/phi)) as defining 7 edge lengths (3 XYZ + 3 face diagonals + 1 body diagonal), and choose those six at a time to get additional phi-scalable tetrahedra, then you've got the gist of David Koski's pioneering explorations.
And remember, two parallel accounting systems: lowest terms in canonical volumes; most economical physical assembly using actual left and right handed modules.