The three processes that dominate short-run plastic manufacturing in 2026 are 3D printing, CNC machining, and injection molding. Rochester businesses come to us regularly asking which one fits a run of 50 custom enclosures, 200 branded keychains, or 30 replacement brackets. The short answer is that each one has a sweet spot — and most people are surprised how far 3D printing's sweet spot has stretched in the last three years.
This is our honest read, written from a Rochester shop that regularly refers work to local CNC shops and traditional molders when it's the right call.
The decision at a glance
- 1 – 5 parts: 3D printing, every time. Nothing else comes close on cost or turnaround at this volume.
- 10 – 100 parts: 3D printing if the geometry is complex or the timeline is tight; CNC if the part is simple, metal, or needs tolerances tighter than ±0.15 mm.
- 100 – 1,000 parts: A toss-up depending on geometry. 3D printing still wins if the part has internal features, undercuts, or multi-material needs. Injection molding starts to break even around 500 units for simple parts.
- 1,000+ parts: Injection molding if the design is frozen and you're committed to the product. Otherwise 3D printing still bridges while tooling is cut.
3D printing vs CNC vs injection molding — side by side
| Attribute | 3D printing | CNC machining | Injection molding |
|---|---|---|---|
| Tooling cost | $0 | Fixturing + programming, low | $8,000 – $80,000 per mold |
| Setup time | Hours | 1 – 3 days | 4 – 10 weeks for tooling |
| Per-part cost (small run) | Low to moderate | High | Very high (tooling not amortized) |
| Per-part cost (high volume) | Flat | Moderate | Very low |
| Break-even quantity | 1 | ~25 – 75 | ~500 – 2,000 |
| Typical tolerances | ±0.1 – 0.3 mm | ±0.025 – 0.1 mm | ±0.05 – 0.15 mm |
| Geometry freedom | Complex internal features, undercuts, lattice | Limited by tool access | Limited by draft, no undercuts without slides |
| Materials | Engineering plastics, some metals (via SLS/DMLS) | Aluminum, steel, brass, titanium, plastics | Thermoplastics, some elastomers |
| Iteration cost | Free — just reprint | Low — re-program | High — re-cut or modify mold |
| Sweet spot | 1 – 500 parts, complex geometry, fast turnaround | 10 – 1,000 parts in metal or tight-tolerance plastic | 1,000+ parts on a frozen design |
3D printing — the short-run workhorse
Cost structure: pay per part, no tooling. That's the entire story. A run of 75 enclosures costs 75× one enclosure, roughly. Setup is measured in hours, not weeks. Design changes between revisions cost nothing — you just reprint.
Where it falters: surface finish on FDM has visible layer lines unless you post-process, and for parts larger than about 300 mm in any dimension the cost starts climbing fast. Tight tolerances below ±0.1 mm are achievable in SLA but generally not in FDM.
CNC machining — when you need metal or sub-tenth tolerances
CNC gives you true metal parts — aluminum, steel, brass, titanium — at tolerances down to ±0.025 mm. For jigs and fixtures that see repeated mechanical stress, or replacement parts that have to bolt into legacy machinery, CNC is often the right answer. Specialty short-run CNC houses like Protolabs publish design-for-machining guides worth skimming before you submit a quote.
Cost structure: setup cost is significant (programming, fixturing, tool paths), then per-part cost is moderate. A run of 10 is expensive per unit; a run of 200 is competitive. Timelines in Rochester are typically 2–4 weeks for small batches.
Injection molding — the volume play
Tooling cost is the story. A simple mold runs $8,000–$15,000 in Rochester; complex multi-cavity tooling can hit $40,000–$80,000. Per-part cost is pennies once you're producing. That tooling bill amortizes over the run, so below roughly 500 units you usually can't justify it.
The other catch is iteration cost. Once a mold is cut, design changes either mean a new mold or a compromise. For a Kickstarter launching in six months with a design still settling, bridging with 3D-printed production lets you ship on day one without committing to a mold you'll regret.
A practical Rochester example
A local food-safety startup needed 300 dispensing nozzles for their pilot launch. Injection molding was quoted at $14,000 tooling plus $0.40 per part (~$120 in material on 300 units) and a 7-week lead time. CNC was quoted at $28 per part (~$8,400) over 3 weeks. We printed the batch in PETG over 9 days at $6.50 per part (~$1,950) with a redesign between unit 50 and unit 51 that improved flow. The startup scaled to injection molding six months later — on a design that had already been validated in market.
When to ask us
If you're staring at a quote from one of these processes and it feels off, send it over with the part drawing and your timeline. We'll tell you honestly if you're in 3D-printing territory or if a different process would serve you better. We work with several Rochester CNC shops and injection molders and can hand work off directly when it's the right call.