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Resin is the right answer for 28 mm miniatures. It is the right answer for a lot of 32 mm work. For fine scatter pieces under 50 mm, for character bases, for ornate door frames and inscribed keystones, resin produces results that FDM cannot match at the same scale. The surface resolution is genuinely better and the detail advantage is real.

Above a certain size, that argument starts to weaken. The same properties that make resin outstanding at small scale create compounding problems at large scale: build volume limits, hollowing complexity, support overhead, FEP wear, and print time all increase faster than the detail advantage grows. Above roughly 150 mm in any dimension, resin usually fails the cost-benefit test on a consumer hobbyist printer. This article explains why that threshold exists, what the failure modes are, and what to do with pieces that exceed it.

Why the threshold exists

Three forcing functions compound as piece size increases. Each one is a manageable cost on its own. Together they change the economics of resin printing in a way that reverses the technology’s advantage over FDM.

Build volume as a hard limit. Consumer resin printers offer a finite build volume, and the usable area for a single large piece is smaller than the nominal spec because pieces need to be tilted to reduce suction forces and distribute weight on the supports. A Mars-class printer with a 143 mm x 89 mm build plate works excellently for 28 mm to 100 mm pieces. A Saturn-class printer with a larger plate extends the upper bound meaningfully, but the printer cost increases to match. Beyond the consumer Saturn range, printer cost climbs steeply for additional build volume. FDM machines in the same price bracket offer 25 to 30 cm cubes of build space with no penalties for using all of it.

Hollowing penalties. A solid 150 mm centrepiece printed in resin uses a significant volume of resin for the interior mass, most of it invisible in the finished piece. The standard solution is to hollow the model before printing: remove the interior material, leave a shell wall of consistent thickness, and add drainage holes so liquid resin can escape. Hollowing recovers the material saving but introduces new failure modes. Drainage holes must be positioned correctly or liquid resin remains trapped inside, where it will eventually crack the shell. Internal supports are needed to prevent large hollow cavities from collapsing during the print. Water-washable resin and hollow models are a particularly bad combination because moisture trapped inside the shell causes cracking from the inside out over days to weeks. The printing bigger and hollow resin miniatures article covers the drainage hole requirements and the water-washable resin warning in full detail.

Support overhead at scale. A standard 30 mm character model carries perhaps 5 to 10 g of support structure that is discarded after printing. A 150 mm centrepiece can carry 50 to 80 g of support, depending on the geometry and tilt angle. That support material is a direct cost: consumed resin that produces nothing usable. Combined with a higher failure rate on larger pieces (more surface area under suction stress, more layers under cure consistency pressure), the waste compounds. A failed large resin print is significantly more expensive than a failed small one.

FEP wear on big plates

FEP wear is a cost that does not show up in the per-gram calculation and accelerates meaningfully on large prints.

Every time a layer cures and the build plate lifts, the print peels from the FEP film. For a small 30 mm character, the contact area of each layer is modest and the peel stress on the FEP is low. For a large piece that fills most of the build plate, the contact area of each layer is much greater and the peel stress is proportionally higher. Big pieces accelerate FEP wear. On a printer running large pieces regularly, FEP replacement can shift from a quarterly maintenance task to a monthly one.

Replacing FEP is not expensive in material cost, but the frequency of replacement on large prints is a real consumable overhead. It is also a hidden depreciation cost on the printer LCD, since large-area prints drive a larger fraction of the screen surface and contribute to uneven wear over time.

Resin print time is determined by layer count and layer exposure time, not by model volume. A larger model does not necessarily print more slowly than a smaller one if it has the same layer count. But a 150 mm centrepiece oriented to minimise supports and reduce peel forces is typically taller on the build plate than a 30 mm miniature tilted at 45 degrees, which means it has more layers and a longer print.

Print times for large resin pieces are long. A 150 mm centrepiece printed solid can take 16 hours or more on most consumer printers. Hollowed and oriented efficiently, perhaps 12 to 14 hours. Cure time per layer cannot be shortened past the resin’s actual exposure tolerance without compromising layer adhesion. Unlike FDM, where layer height and print speed offer real time budget control, resin print time at scale is relatively inflexible.

A 16-hour resin print is also a 16-hour window for failure. Power interruptions, temperature variation affecting resin cure consistency, and FEP delamination on the last third of a long print are all failure modes that are simply less relevant on a 3-hour small-miniature print.

The honest size thresholds

The decision is not binary, and the threshold is directional rather than a hard engineering limit. Think of it as a three-zone framework.

Under roughly 80 mm in any dimension. Resin almost always wins here. The build volume is well within consumer printer limits, hollowing is optional rather than mandatory, support overhead is manageable, and the detail advantage over FDM is cleanest at this scale. The resin cornerstone and the general framework in resin or FDM for tabletop terrain apply directly.

Roughly 80 to 150 mm in any dimension. Case by case. Detail level, painted look, transport durability, and whether the model is hollow-printing friendly all affect the decision. A 100 mm ornate dungeon gate with good hollow geometry and clear drain-hole placement may be worth the resin investment. A 120 mm roughly textured terrain boulder has no detail that earns the resin overhead. Use the piece’s detail requirements and your own experience with your printer to make the call.

Above roughly 150 mm in any dimension. FDM by default, unless detail is the dominant variable and you accept the full cost. At this scale, the compounding of build volume, hollowing, support overhead, FEP wear, and print time typically means FDM produces a better result per hour and per dollar. The detail argument for resin weakens at large scale too: at 200 mm, hand-painted detail on a smooth FDM surface can reach a higher visual ceiling than printed detail on a rough resin print, because the scale changes what painting can add to the piece.

The 150 mm figure is editorial and not a hard physical boundary. Your specific printer, your resin, your model geometry, and your tolerance for post-processing all move the threshold. Use the figure as a starting assumption and adjust based on experience.

The split-piece exception

The most practical workaround for pieces that exceed the resin size limit is to split them. A 200 mm centrepiece vehicle can be divided into a resin top half and an FDM base, joined invisibly under primer and paint. The resin half carries the detail-rich visible surface. The FDM half provides the mass, structural base, and cost savings.

Both Lychee (resin slicer) and Bambu Studio (FDM slicer) have cut-plane tools that allow you to set the same Z value in both, producing two halves that join cleanly. Adding a 2 to 4 mm peg or pin geometry at the split plane gives a registration point for assembly that prevents the halves from sliding during gluing.

The split approach halves the resin volume and most of the support overhead on the top half, while the FDM base prints cheaply and without post-processing complexity. Total cost and print time drop significantly compared with printing the whole piece in resin. The technique is covered fully in FDM base, resin top: splitting big models.

The painted-versus-printed-detail trade

This is the argument that is least discussed in the resin versus FDM debate and most relevant above 100 mm in scale.

At 28 mm, printed detail is the dominant visual contributor. The scale is too small for brushwork to add significant texture that was not already printed into the surface. Resin’s resolution advantage at 28 mm is therefore a genuine and significant advantage.

At 150 mm or 200 mm, the balance shifts. At that scale, a skilled painter adds highlights, washes, wetblending, and surface effects that are visually more significant than the printed detail in the model. An FDM surface at 0.08 mm layer height, printed at a scale where layer lines are already less visible, primed and painted, can carry a painted finish that reads as well or better than a resin surface with the same painted treatment.

This does not mean FDM is better than resin at large scale for the quality ceiling. It means the gap is smaller than at small scale, and the gap shrinks faster than the cost and time advantage of FDM grows. Above roughly 150 mm, the practical case for resin depends almost entirely on whether the model contains fine sub-3 mm detail that must be printed rather than painted. Faces, inscriptions, and thin filigree still justify resin at any scale where they appear. Plain surfaces, broad architectural geometry, and rough texture do not.

Avoiding the most expensive mistake

The most expensive decision in large-piece resin printing is not choosing resin over FDM. It is choosing resin, committing to a full set of large pieces, printing half of them successfully, and then encountering a failure mode that costs a screen replacement or a full-plate resin pool on the build surface.

The failure modes that bite hardest on large resin pieces are: inadequate support on the first layers of a heavy model (catastrophic early failure, often with FEP damage), trapped resin in a hollow piece printed in water-washable resin (cracking failure after the piece is painted and on the shelf), and scaling a pre-supported file beyond its designed scale (supports undersized, model fails at the support attachment points mid-print).

All three are preventable with good technique. But they are worth naming directly because the cost of getting them wrong compounds with piece size in a way that small-miniature printing does not prepare you for.

For the Elegoo Saturn 4 Ultra and similar Saturn-class printers, the larger build plate genuinely extends the upper bound of what resin can produce without the most painful compromises. If you are regularly working with 100 to 150 mm pieces, a Saturn-class machine changes the maths compared with a Mars-class printer. Above 150 mm, the improvements are incremental.

Closing

Resin is the right answer until size flips it. The threshold is roughly 150 mm in any dimension, and it is not a bright line but a zone where the case for resin weakens faster than the case for FDM strengthens. Below 80 mm, use resin with confidence. Between 80 and 150 mm, the decision belongs to the specific piece. Above 150 mm, default to FDM and reserve resin for the detail-critical components, or split the piece using the FDM base, resin top approach. The cost comparison article works through the economics across both technologies in full, including the hidden costs that the per-gram figure misses.