Great question – this is where design intent collides with machining reality. If it’s 3-4 well-controlled orientations on a 5-axis, that’s normal. If you’re into 6+ flips with soft jaws, re-indicating datums, and creative fixturing, that’s when cost and tolerance stack-up start creeping in.

There’s no hard rule, but here’s a practical one: if you’re creating custom fixtures just to access features – and those fixtures cost more than the assembly hardware would – it’s time to reconsider splitting the part.

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.