Snapshots after ∼5,000,000 Monte Carlo trial moves per particle, starting from a random initial configuration, for the interaction models with nonpatchy (A) and patchy (B) segmental interactions at a segmental interaction energy of ε = 8 kBT. Whereas the model with nondirectional interactions yields chainlike aggregates of various shapes (two isolated clusters are shown in Fig. 2), the model with directional interactions readily self-assembles into near-spherical cages of fairly uniform size (two isolated cages are shown in Fig. 6). The actual simulation boxes are approximately four times as large, containing 104 particles at a density of 10−3σ−3 corresponding to the critical assembly concentration of ∼100 μg/ml.