In one implementation, a connection system includes an adapter block assembly (130, 160) and methods for making thereof. In one aspect, the adapter block assembly (130, 160) includes a plurality of adapters (20), each of which having a slot structure (50). The adapter block assembly 130 can be built by providing a support structure (100) having a plurality of extension members (102) that engage with the adapter slot structures (50). In one implementation, a flange clip (200, 220) is removably inserted into the slot structure (50), wherein the flange clip (200, 220) has a second width (W3, W4) that is greater than first width (W1).