Buy a 3D printer or use a 3D printing service?

The first number that matters is not the printer price. It is how many parts you will actually print in a year, and how many of them share the same geometry. If you print 20 brackets a year, a desktop machine sits idle for 350 days and still needs filament storage, nozzle changes, and calibration. Print 20 brackets a week with design changes between runs and ownership starts to look reasonable.

Model the real annual cost: machine, spare nozzles, build plates, drying equipment for hygroscopic filament, software licence, floor space, and the hours your engineer spends slicing and re-printing failed builds. For most small teams that total lands between two and five times the sticker price over three years. A service invoice is smaller and arrives only when you have a part to make.

Break-even usually falls somewhere between 150 and 400 parts a year for FDM work, and later for resin or metal. Below that range, the service wins on cash. Above it, and when the geometry repeats, ownership wins on turnaround. The crossover moves with part size, because a large build volume machine costs far more than a 200 × 200 mm bed.

One more input: how fast your design changes. A team that revises a housing every week gets more value from a machine on the bench than from a purchase order cycle. A team that freezes a design and needs 30 copies has no reason to own hardware.

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  Low volume, high mixService. You pay per part, no idle time.
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  High volume, fixed geometryOwnership can pay back within a year.
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  Regulated partsService, unless you can qualify the process in-house.
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  Design still movingOwnership shortens the loop between revisions.

Filament choice on a desktop FDM machine is wide but shallow. PLA, PETG, ABS, ASA, TPU, and some filled grades run well. Engineering materials such as PEEK, PEI, and carbon-fibre reinforced PA need a heated chamber above 200 °C, a hot end that reaches 400 °C or more, and controlled cooling. Those machines cost an order of magnitude more than a hobby unit, and they are not a casual purchase.

A service runs the full spread: FDM in engineering thermoplastics, SLA and DLP in photopolymer resin, SLS in PA12 and glass-filled nylon, MJF, and metal processes such as DMLS in Ti-6Al-4V, 316L, and aluminium alloys. If your part has to survive under a hood, sit in a sterilizer, or hold a thread, the material list often decides the sourcing route before cost does.

Think about what the part has to survive, not what sounds advanced. A jig that holds a sensor for one afternoon can be PLA. A duct that sees 120 °C under a car hood cannot. An implant trial that touches tissue needs a qualified resin and a paper trail. Match the material to the duty cycle and the paperwork, and the buy-or-outsource question often answers itself.

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  PLA / PETGConcept models and shop fixtures. Low heat resistance.
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  ABS / ASA / PCFunctional enclosures. Needs an enclosed machine.
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  PA12 (SLS / MJF)Ducts, clips, living hinges. No support removal.
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  Ti-6Al-4V, 316L (DMLS)Metal prototypes. Service only for most teams.

FDM holds roughly ±0.5% of a dimension, with a floor around ±0.2 mm on a well-tuned machine. SLS and MJF land near ±0.3% or ±0.3 mm, whichever is larger. SLA can reach ±0.1 mm on small features. Layer lines stay visible unless you sand, vapor-smooth, or tumble the part, and those steps add labor that rarely shows up in a hobby budget.

CNC machining is a different class. At GreatLight we hold ±0.005 mm (±0.0002 in) on milled and turned features, with finishes from Ra 1.6–3.2 μm as machined down to Ra 0.2–0.8 μm when polished. If a bore has to take a bearing, a face has to seal against an O-ring, or two parts have to mate without a gap, printed plastic will not get you there.

The usual path is to print for form and fit, then machine for function. Print the housing to check cable routing and connector clearance, then cut the same geometry from 6061-T6 or 17-4PH once the layout is frozen. Use the cheap process to learn, and the accurate process to deliver.

Threads deserve their own note. Printed threads below M6 strip easily and lose pitch accuracy. Design a printed pilot hole and cut the thread with a tap, or use a heat-set insert. If the joint carries load, machine the boss.

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  Form and fit checkPrint. Fast and cheap.
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  Sealing face or bearing boreMachine. ±0.005 mm.
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  Threaded joints under loadMachine or use inserts.
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  Cosmetic coverPrint, then sand or smooth.

A printer on your bench gives the shortest feedback loop. Slice in the morning, hold the part after lunch. That matters when you are chasing an interference you cannot see in CAD. The service route adds shipping and queue time, but it also adds capacity you do not have to staff, and it keeps running while your team sleeps.

Confidentiality decides the route for some programs. Sending an unreleased housing to an outside shop means the file leaves your building. Ask for an NDA before the first upload, and check how the supplier stores and deletes your data. GreatLight works under NDA on request and holds ISO 27001:2022 for information security, which covers how files are handled, not just how parts are made.

Hidden overhead is where ownership surprises people. Consumables, failed prints, nozzle wear, calibration time, and the space a machine takes up all land on your books. A service bundles those into the part price. Neither is free; one is just easier to see.

Volume is the last lever. Small runs rarely justify staffing a print farm. Once you pass a few thousand identical parts, injection molding or die casting usually beats both routes on unit cost, and we quote those alongside CNC when the quantity supports it.

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  Same-day iterationOwnership. No shipping, no queue.
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  Unreleased designsService under NDA, with ISO 27001 controls.
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  Burst capacityService. No hiring, no idle machines.
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  Above 10,000 partsLook at molding or casting, not printing.

Write down five numbers: parts per year, number of design revisions, largest part dimension, required tolerance, and whether the part carries load or seals. Those five answers sort most projects in under ten minutes. High revision count and small parts point to ownership. Tight tolerance, metal, or regulated use points to a service.

If the part is plastic and cosmetic, print it. If it is plastic and functional, print a prototype and plan a machined version. If it is metal, or it has to hold ±0.005 mm, skip the printer and quote the machining. Mixing processes across a program is normal and often cheaper than forcing one route onto every part.

Send the STEP file and the drawing with tolerances, even for a print job. Suppliers who quote both printing and machining will tell you which process holds the critical dimension and which one only needs to look right. That feedback is worth more than a small unit-price difference.

When you are ready, we quote 3D printing and CNC from the same upload, with free DFM analysis inside 12 hours and no minimum order quantity, from one prototype to 10,000+ parts.

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  Plastic, functionalPrint for fit, machine for function.
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  Metal or ±0.005 mmMachine it.
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  Mixed programSplit the parts by process.