3D printing (SLS) is cheaper than CNC machining for complex geometries, small runs up to roughly 100 parts, and designs with internal channels, cavities or organic shapes. CNC remains cheaper for simple geometries from block material, large runs, and for metal alloys that SLS does not offer.
Where does 3D printing win?
3D printing beats CNC at:
- Complex internal geometry: cooling channels, manifold routings, organic airflows — impossible or very expensive on CNC
- Topology-optimised designs: organic “bone structure” maximising strength-to-weight — literally not machinable on CNC
- Multi-component assemblies as a single print: hinge, ball pin and housing printed together — saves assembly
- Short runs (1-100 units): no setup, no fixtures, no toolpaths
- Fast iterations: tweaking the design takes minutes, no tool rework
For designers, this also means fewer design constraints: forget workholding, forget tool reach, forget undercuts. Print what you want to design.
Where does CNC win?
CNC machining remains economically better for:
- Simple geometries from block material: flanges, plates, brackets with flat surfaces
- Metal alloys: aluminium, steel, stainless, brass — SLS offers no metals
- High surface quality: Ra < 1.6 μm straight from the machine
- Long runs >500 units of simple parts where tooling is minimal
- Tolerances tighter than ±0.05 mm: SLS typically achieves ±0.1-0.3 mm
- Parts carrying heavy thread loads: solid metal rather than polymer
For hybrid strategies, combine both: print the complex part in SLS, machine the mating part in CNC metal.
How do you compare the price yourself?
Simplest check: get a quote from both processes and compare. Our SLS instant quote is online immediately. CNC shops usually need 1-2 days for an offer.
As a rough rule of thumb:
- Volume under 100 cm³, complex: SLS almost always cheaper
- Volume 100-1,000 cm³, complex: SLS competitive; simple: CNC competitive
- Volume above 1,000 cm³: depends strongly on geometry and material
Don’t compare just price — also compare lead time and design freedom. A 30% more expensive SLS part that arrives 2 weeks earlier, or has a better geometry, can be cheaper net.