That’s a great question – this is where design intent collides with the reality of manufacturing. If you find yourself in a tightly controlled 5-axis process with 3-4 orientations, that’s normal. If you’re dealing with 6+ rotations using soft jaws, resetting references, and creative fixturing, that’s when cost and tolerance stack-up start to increase.

There’s no hard and fast rule, but here’s a practice: if you’re creating special devices to access features – and these devices are more costly than the assembly hardware – it’s time to rethink the part division.

Sealing and IP Rating: If the enclosure needs to be waterproof (IP67+) or airtight, a single piece eliminates leak paths.Structural Integrity: For high-vibration or high-stress environments, a single block is inherently stronger.EMI/RFI Shielding: Fewer seams mean better electromagnetic interference protection.Precision: If features on opposite sides have extremely tight tolerances relative to each other (e.g., $< pm 0.02$ mm), machining them in one part (using a 5-axis machine) is more accurate than trying to align two bolted parts.