FDM or SLA or SLS: Which is Right for You?
Updated
Every 3D printing job really answers two questions, in order: should this part be printed at all, and if so, by which process. The same part can be printed five ways, and the process decides how it looks, how strong it is, what it costs and when you get it. The photo above is one frame printed three ways.
Should you 3D print this at all?
Printing wins on complexity, speed and small numbers. It loses on simple shapes, tight tolerances and volume, and we would rather say so at the quote than after you have paid for it.
Print it when
- You need the part this week, not after a mould is built
- The shape has undercuts, internal channels or lattices a cutting tool cannot reach
- You want a handful or a small run, so there is no tooling to pay off
- Every piece is different
Another route wins when
- The part is a simple solid shape a cutting tool can reach, and CNC machining holds tolerances to ±0.05 mm
- You want 20 to 500 copies of one part, where vacuum casting in silicone prices the mould once, then each cast per piece (pricing)
- You want about 1,000 units or more, where injection moulding takes over
- The surface has to be moulding-smooth with no finishing
If printing is the right call, let the job pick the process: filament for most parts and the biggest pieces, resin for fine detail and a smooth surface, nylon powder for parts that have to work, and metal for heat, load and wear. In a hurry? Answer five questions and we will name one for you.
Fused Deposition Modeling (FDM)
Filament printing: melted plastic, laid down line by line. It is the cheapest process, it prints the biggest pieces, and it takes the widest range of materials, which is why most parts start here. Switch to resin when the surface matters more than the price, and to nylon powder when the part has to work rather than just look right.
Good at
- The lowest price per part, because PLA is the cheapest material per gram (pricing)
- Big pieces, split and bonded when they outgrow the bed
Not so good at
- Layer lines show, so a smooth painted finish means sanding first
- Parts can split along the layers under load
- Fine features and thin walls get lost
Where we use it
- Prototypes, jigs and fixtures
- Architectural models and display pieces
- Low-volume parts in PLA, ABS, PETG, nylon or TPU
Stereolithography (SLA)
Resin printing: liquid resin cured by a laser. It holds the finest detail of anything we run and comes off the printer smooth, so it needs no sanding before paint. It is the opposite trade to nylon powder: resin gives you the surface and chips under load, nylon gives you the toughness and a fine grain.
Good at
- Detail down to about 0.1 mm, smooth straight off the printer
- Clear and translucent parts, though how clear a print really gets depends on the finishing
Not so good at
- Resin is brittle, so it chips where plastic would bend
- Parts need washing and curing, which adds a day
- Size depends on the resin, so a big clear or flexible piece may have to be split
Where we use it
- Figurines, miniatures and display models
- Dental and jewellery work
- Masters for silicone moulds and casting
Selective Laser Sintering (SLS)
Nylon powder printing: a laser fuses nylon powder, and the loose powder holds the part up. No supports, nothing to cut off, and the part is equally strong in every direction. More on SLS nylon printing. SLS and Multi Jet Fusion (MJF) print the same nylon, so the choice is volume: SLS is cheaper for one or two, MJF for a batch that has to match.
Good at
- Strength that is the same in every direction
- Hinges, snap fits and moving assemblies, printed already assembled
Not so good at
- The surface has a fine grain rather than a polish
- Parts cool in the powder before they ship, so allow a few more days
- Natural or dyed colours only
Where we use it
- Functional parts that have to work, not just look right
- Brackets, housings and clips for real use
- Small runs of end-use parts
Multi Jet Fusion (MJF)
The same nylon powder, fused by heat and a printed agent instead of a laser. Finer detail than SLS, and every part comes out like the last one, which is what a batch needs.
Good at
- Batches where each part has to match the last
- Finer detail and a cleaner surface than SLS
Not so good at
- It costs more than SLS
- The practical colour range is grey to black
- Overkill for a single prototype
Where we use it
- Low-volume end-use parts and enclosures
- Lattices, vents and grilles
- Functional prototypes going to a customer
Selective Laser Melting (SLM)
Metal printing: stainless, aluminium or titanium, for parts that have to take heat, load or wear that no plastic survives. See metal 3D printing for what we run and what it suits. We usually prove the fit in FDM first, because a plastic test print costs a few dollars and a metal one does not.
Good at
- Heat, load and wear, in real metal
- Shapes a cutting tool cannot reach
Not so good at
- The most expensive route, by a distance
- The slowest: lead time is measured in weeks
- Sealing faces and threads are machined after printing
Where we use it
- Replacement parts that are no longer made
- Brackets and mounts that live inside a machine
- One-offs where tooling makes no sense
Still not sure? Answer five questions
The five side by side
| Process | Materials | Best for | Cost | Lead time |
|---|---|---|---|---|
| FDM | PLA, ABS, PETG, nylon, TPU | Prototypes, jigs and fixtures, large pieces | Lowest per gram | Shortest |
| SLA | Standard, tough, flexible, clear and castable resins | Figurines, dental and jewellery, casting masters | Two to three times FDM | Short |
| SLS | PA11, PA12 nylon, TPU | Functional parts, hinges and snap fits | Four to six times FDM | Medium |
| MJF | PA11, PA12 nylon | Matching batches, low-volume end-use parts | Above SLS | Medium, shorter than SLS |
| SLM | Stainless, aluminium, titanium | Heat, load and wear, obsolete parts | Quoted per job | Longest |
We run all of them, so one quote covers the lot, and a job can mix them: an FDM body with a resin face, or a prototype in FDM that moves to MJF once the design is settled.
Frequently asked
Which 3D printing technology is cheapest in Singapore?
FDM is the cheapest per part, because PLA is the cheapest material per gram, though geometry and infill move the final figure. SLA resin costs two to three times as much per gram as FDM, and SLS nylon four to six times as much; the pricing page has the current rates. Use FDM for concept models, fixtures, and large pieces, and step up to SLA, SLS or MJF only when surface finish or material properties demand it. Metal is priced per job rather than per gram.
When should I choose SLA over FDM?
Pick SLA resin when (1) the part has fine detail under 0.5 mm, (2) you need a smooth surface that paints cleanly without sanding, (3) you're casting from it (silicone moulds love SLA masters), or (4) it's a clear or translucent piece. SLA's downside is brittleness, so don't use it for parts that flex or take impact.
Is SLS worth it for prototypes?
SLS nylon is overkill for one-off prototypes, since at four to six times the cost of FDM you're paying for production-grade durability you don't yet need. It earns its price on living-hinge parts, snap-fits, and small-batch end-use parts where FDM layer adhesion would fail. For a first prototype, FDM almost always wins.
When does 3D printing lose to CNC or injection moulding?
3D printing usually loses on simple, solid shapes and on high volumes. CNC machining holds tighter tolerances (down to ±0.05 mm) and is often cheaper for a part you could hold in a vice and reach every feature with a cutting tool. Injection moulding takes over at roughly 1,000+ identical units, with the crossover landing somewhere between 500 and 2,000 depending on geometry; below that, silicone moulding (the mould is priced once, then each cast is priced per piece) usually wins for the 20 to 500 unit range. We'll flag which route is cheaper for your numbers at quoting.
When is metal 3D printing worth it over a plastic part?
Metal earns its cost when the part has to survive heat, load or wear that no plastic will take, or when the shape is one a cutting tool cannot reach. Metal is quoted per job, not per gram, because the alloy, the part's size, the finishing and the quantity all move the price. Send the file, the metal you want and the faces that have to be exact, and we come back with a firm quote, usually within 24 hours.
What's the difference between SLS and MJF?
Both fuse nylon powder with no support structures needed, so parts nest freely and interlocking assemblies print in one shot. MJF (HP's Multi Jet Fusion) generally holds finer detail, more consistent mechanical properties and a shorter lead time than SLS. SLS remains the workhorse for straightforward functional parts; MJF earns its place on higher-detail or higher-consistency functional batches.
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