Subtract from solid. Or build up layers. When each wins.

For plastic prototypes (1–10 pieces), 3D printing is usually cheaper — no setup cost, direct from CAD. For metal prototypes, CNC is often cheaper even at quantity 1 because metal 3D printing (DMLS) is extremely expensive ($500+ per small part). For medium quantities (10–100), CNC machining typically wins on cost regardless of material.

Sometimes — depends on application. MJF nylon parts can replace injection-molded or machined nylon in many functional applications. DMLS titanium parts can replace machined titanium for complex aerospace geometry. But 3D printed parts generally have: 5–20% lower strength, 2–5× higher surface roughness, larger tolerance band. If the design is tolerance-critical or strength-critical, CNC remains the safer choice.

Hybrid approaches are increasingly common. Example: DMLS prints complex Inconel geometry (internal cooling channels), then CNC finishes critical mating surfaces to tolerance. Or SLS prints rough-form plastic part, then CNC drills precision holes and threads. This combines 3D printing's geometry freedom with CNC's precision. We offer both processes in-house for integrated workflows.

3D printing typically wins for single parts — no setup, no programming, just print-and-ship. SLA resin: 24 hours possible. SLS/MJF nylon: 48–72 hours. CNC single parts: 3–7 days typical. However, at quantities above 5–10, CNC catches up because setup amortizes across multiple parts while 3D printing time scales linearly with part count.

CNC from wrought metal — always. Wrought aluminum 7075-T6: 503 MPa yield. DMLS printed 7075 equivalent: 380–420 MPa yield (15–25% less). Similar reductions in other metals. For structural parts where strength is critical, CNC wins. For parts where geometry is more important than maximum strength, 3D printing wins.

CNC generates metal chips (recycled). 3D printing generates less waste per part but uses more energy per unit volume. Powder bed fusion (SLS, DMLS) has powder handling issues. For high-volume production, CNC is typically more efficient overall. For low-volume with complex geometry, 3D printing wins. Both are order-of-magnitude better than die casting or injection molding in terms of tooling energy.