How each technology works
FDM — layer by layer from a spool
In FDM printing, a motorized extruder pushes a thermoplastic filament through a heated nozzle. The nozzle traces paths across a build plate, depositing molten plastic that solidifies almost immediately. Once a layer is complete, the build plate (or the gantry) moves by the layer height — typically 0.1 mm to 0.3 mm — and the process repeats. The resulting surface shows visible layer lines, which can be sanded or smoothed with acetone depending on the material.
The mechanical simplicity of FDM makes it easy to maintain. Nozzles, PTFE tubes, and extruder gears are all replaceable parts available from general electronics suppliers. In Poland, components for popular machines like Prusa MK4 or Bambu Lab X1 are stocked by local resellers including Botland, Allegro, and Kamami.
Resin — cured by light
MSLA (Masked Stereolithography) and DLP (Digital Light Processing) printers work differently. Instead of extruding material, they cure liquid photopolymer resin using UV light — either a masked LCD screen (MSLA) or a projector (DLP). The build plate descends into a resin vat, and each layer is cured in a single exposure, meaning the full layer is produced at once regardless of its complexity.
This produces dramatically finer detail than FDM. Layer heights as low as 0.025 mm are common. The trade-off is that parts must be washed in isopropyl alcohol and cured under UV light after printing. The resin itself is chemically reactive before curing and requires nitrile gloves and adequate ventilation.
Print quality and resolution
FDM resolution is limited primarily by nozzle diameter and layer height. A standard 0.4 mm nozzle at 0.2 mm layer height produces functional parts with visible layer lines. Smaller nozzles (0.25 mm or 0.2 mm) improve detail but slow print speed and increase the risk of clogging with certain materials.
Resin printers produce near-isotropic quality in XY by virtue of the LCD mask, with pixel sizes around 0.035–0.05 mm on current mid-range machines. For miniatures, dental models, jewelry prototyping, and parts where surface texture matters, resin has no real equivalent at comparable price points.
For mechanical parts where dimensional accuracy, layer adhesion under stress, or specific material properties (flexibility, high-temperature resistance) matter more than surface texture, FDM remains the more practical choice.
Material options
FDM filaments span a wide range: PLA for prototyping, PETG for functional parts with slight flexibility, ABS and ASA for higher-temperature environments, TPU for elastic components, and engineering-grade materials like PA12 (nylon), PC, and carbon-fiber-reinforced variants for demanding applications. Material switching requires little more than changing the temperature profile in the slicer.
Resin materials are more limited in mechanical performance. Standard resins are brittle once cured. ABS-like, flexible, and high-temperature resins exist, but they cost significantly more than FDM equivalents and still do not reach the tensile strength of FDM-printed nylon or polycarbonate. The primary exception is engineering resins used in dental and jewelry industries, where the dimensional precision of resin is irreplaceable.
Post-processing requirements
FDM
Most FDM prints require support removal, which ranges from trivial (PVA water-soluble supports, or breakaway supports on dual-extruder machines) to tedious (dense support structures in hard-to-reach cavities). Beyond that, FDM parts are ready to use immediately — no washing, no UV curing.
Resin
Every resin print goes through a post-processing sequence before it is safe to handle and dimensionally stable. The part must be washed in IPA or a dedicated washing solution (e.g., Elegoo Washing & Curing stations use IPA) to remove uncured resin residue, then exposed to UV light for a defined period to complete polymerization. Skipping either step produces tacky, undersized, or brittle parts.
Resin waste — contaminated IPA, failed prints, used vat liners — must be UV-cured before disposal to neutralize the photopolymer chemistry. This is both an environmental consideration and a practical workflow step that FDM users do not need to manage.
Running costs
Entry-level FDM filament (PLA) from established brands (Prusa, Bambu, Fiberlogy) costs roughly 60–90 PLN per 1 kg spool in Poland. A kilogram produces a substantial number of parts — a standard 20% infill object roughly the size of a fist might use 100–150 g.
Resin is sold by volume. Basic resins from Elegoo or Anycubic run 80–120 PLN per litre in Poland. Consumption is often comparable to filament by weight, but the addition of failed prints (which are more common on resin machines, particularly during initial calibration) and the cost of IPA for washing pushes running costs higher.
Which printer for which use case
- Prototyping structural parts: FDM with PETG or ABS. Faster iteration, lower cost, usable immediately.
- Miniatures, dental models, jewelry: Resin. Detail at this scale is not achievable with FDM.
- Large functional enclosures or brackets: FDM. Resin build volumes are typically smaller than mid-range FDM machines.
- Flexible components: FDM with TPU. Flexible resins exist but are more expensive and harder to print reliably.
- Multi-material prints: FDM with dual extrusion (e.g., Prusa XL, Bambu AMS). No resin equivalent at consumer prices.
For makers in Poland new to 3D printing, FDM remains the more forgiving starting point. The material ecosystem is wider, the machines are easier to repair, and the workflow requires no chemical safety precautions beyond standard workshop hygiene. Resin printing is a meaningful addition once specific detail requirements justify the more involved post-processing routine.
External reference: RepRap Wiki — Fused Filament Fabrication