Hierarchical Assembly
Hierarchical assembly builds structures through multiple scales: small assemblers compose small blocks into larger blocks, which become the building material for larger assemblers, and so on. Each level up reduces travel distance per unit of material moved.
The principle
A single small robot building a large structure wastes most of its time traveling. A larger robot can carry a pre-assembled chunk in one trip instead of many. The key insight: the larger robot itself can be built by the smaller robots from the same discrete modular materials.
Biological analogy
Biology does this naturally: ribosomes assemble amino acids into proteins, proteins into organelles, organelles into cells, cells into organs. At each level, the “assembler” is built from the output of the previous level. The result is exponential throughput scaling across orders of magnitude (Abdel-Rahman et al.).
Combined with self-replication
Hierarchy alone keeps throughput constant — a single large robot is faster per trip but still serial. Combined with self-replication (making more robots at each level), throughput scales as O(2^N) — see exponential assembly scaling.