Reference

3D printing glossary: 120+ terms in plain English

This 3D printing glossary defines more than 120 FDM, slicer, resin, multi-material and CAD terms in plain English, from 3MF to Z-offset. Where beginners commonly get tripped up, there's a short note. Search or use the A–Z bar to jump to a term.

18 min read Updated October 2026 All levels Reference · 1 of 1

0–9

3MF: 3D Manufacturing Format. A zipped package that stores meshes together with units, colors, materials, multiple parts and often slicer settings. It's the native project format of Bambu Studio, OrcaSlicer and PrusaSlicer, and the best choice for multicolor models. See 3D printing file formats.

A

ABS: Acrylonitrile butadiene styrene. Tough, heat-resistant filament printed at about 235–255 °C on a 95–110 °C bed with little or no part cooling. It warps without an enclosure and gives off styrene fumes, so ventilate.
Acceleration: How quickly the toolhead changes speed, in mm/s². Higher acceleration shortens prints, especially small ones, but shakes the frame more. Input shaping lets you raise it without ringing.
Adaptive layer height: A slicer feature that uses thin layers on curves and slopes and thicker layers where walls are straight, saving time without visible stair-stepping. PrusaSlicer calls it variable layer height; Cura calls it adaptive layers.
AMS (Automatic Material System): Bambu Lab's family of multi-material feeders. The AMS and AMS 2 Pro hold four spools each (the 2 Pro also dries them), the AMS HT holds one spool and dries at higher temperatures, and the AMS lite is an open four-spool unit for the A1 series. Several units can be chained on supported printers. See the multicolor 3D printing guide.
Annealing: Heating a finished part below its melting point so the plastic relaxes or crystallises, improving heat resistance and sometimes strength. Temperature and time depend on the material; expect some shrinkage and possible warping.
Arachne: A wall generator that varies line width along a wall so thin and tapering features fill cleanly instead of leaving gaps. The default in Cura since 5.0 and PrusaSlicer since 2.5, and available as a wall generator option in Bambu Studio and OrcaSlicer.
ASA: Acrylonitrile styrene acrylate. Like ABS but far more UV-resistant, so it's the usual choice for outdoor parts. Prints at about 240–260 °C on a 100–110 °C bed, ideally in an enclosure.

B

Bed: The flat, usually heated platform a print is built on, typically topped with a removable flex plate.
Bed leveling: Making the nozzle follow the bed at a constant height. Most modern printers probe the bed and compensate in software (mesh leveling) rather than relying on perfectly adjusted screws. See bed leveling and Z-offset.
Bed slinger: Slang for a printer whose bed moves back and forth along Y, such as Ender-style, Prusa MK-series and Bambu Lab A1 printers. Simple and affordable, but moving the bed and part limits acceleration.
Belt: The toothed rubber belt that turns motor rotation into axis motion. GT2 (2 mm pitch) is the common profile, and correct tension matters for accuracy.
Benchy: The "3DBenchy" tugboat, a standard test print packed with overhangs, bridges, holes and small details. If your Benchy prints well, most things will.
BOSL2: The Belfry OpenSCAD Library, version 2: a large open-source OpenSCAD library with rounding, attachments, threads, gears and many ready-made shapes. See OpenSCAD libraries.
Bowden: An extruder setup where the motor sits on the frame and pushes filament through a PTFE tube to the hotend. The toolhead is lighter, but retractions are longer and soft TPU is hard to push.
Bridge / bridging: Printing a straight span across a gap between two supported edges. Many printers bridge 10–20 mm cleanly with good cooling; well-tuned machines go further.
Brim: Extra loops of plastic attached around the base of the first layer to increase grip and resist warping. Snap or trim it off afterwards.
BVOH: Butenediol vinyl alcohol copolymer: a water-soluble support material like PVA that dissolves faster. Very moisture-sensitive, so store it sealed and dry.

C

Cartesian: Printer kinematics where each axis is driven by its own motor along a straight line. Bed slingers (i3-style printers) are the most common Cartesian design.
CFS (Creality Filament System): Creality's four-spool multi-material feeder for its K2 series and other recent printers. Up to four units can be combined for 16 filaments.
Cold pull: Cleaning a nozzle by heating filament inside it, letting it cool partway, then pulling it out so debris comes out with it.
CoreXY: Kinematics where two motors work together through crossed belts to move the toolhead in X and Y, while the bed moves only in Z. The light moving mass allows high acceleration. Used by Voron, Bambu Lab X1, P1 and H2 series, and Prusa CORE One printers.

D

Direct drive: An extruder mounted on the toolhead right above the hotend. It allows short retractions and is the easiest way to print flexible TPU, though some Bowden printers manage harder TPU slowly.
Dual extruder: Any printer with two nozzles, either on one toolhead (such as the Bambu Lab H2D) or on independent carriages (IDEX). Idle nozzles can ooze, so a small prime tower is common.

E

Eddy current probe: A non-contact bed probe that senses the metal bed with an induction coil and can map it very quickly. Klipper supports eddy current probes (such as LDC1612-based boards) for homing and bed meshes.
Elephant's foot: The first layers bulging outward because they're squished and stay soft on the hot bed. Fix it with a slightly higher Z-offset, a cooler bed or the slicer's elephant foot compensation.
Enclosure: A box around the printer that keeps heat in (important for ABS, ASA, PC and nylon) and helps contain fumes and particles.
E-steps: Marlin's extruder steps per millimetre: the value that turns a requested filament length into motor steps. Calibrate it so 100 mm requested really is 100 mm extruded. Klipper uses rotation distance instead.
Extruder: The motor and gear assembly that grips the filament and pushes it into the hotend.

F

FDM / FFF: Fused deposition modeling / fused filament fabrication: building a part by melting thermoplastic filament and laying it down layer by layer. They mean the same thing; "FDM" is a Stratasys trademark, so "FFF" became the generic name.
Filament: The thermoplastic strand that feeds the printer. 1.75 mm is standard on almost all consumer printers; 2.85 mm survives on some older and UltiMaker machines.
Filament runout sensor: A switch or motion sensor that notices when filament runs out or stops moving and pauses the print so you can load a new spool.
First layer: The bottom layer of a print. It decides bed adhesion, and most failed prints fail here.
Flex plate: A removable spring-steel sheet with a PEI or other coating. Flex it and finished prints pop off.
Flow rate: An ambiguous term. Physically it means volumetric flow in mm³/s. In Cura, the setting called Flow is a percentage multiplier on extrusion, which other slicers call flow ratio or extrusion multiplier.
Flow ratio / extrusion multiplier: A multiplier that fine-tunes how much plastic is extruded, usually close to 1.0 (100%). Called Flow in Cura, extrusion multiplier in PrusaSlicer and flow ratio in Bambu Studio and OrcaSlicer. Calibrate it per filament.
Flushing volume: The amount of filament purged when a multi-material printer switches from one color to another, set for each color pair. Dark to light needs the most. PrusaSlicer calls these purging volumes.
Fuzzy skin: A slicer option that adds small random jitter to outer walls, giving a matte, textured surface that hides layer lines and fingerprints.

G

Gantry: The frame and rails that carry the moving toolhead across the printer.
G-code: The plain-text machine instructions a slicer produces and a printer follows. A line like G1 X100 Y100 F3000 means "move to X100, Y100 at 3,000 mm per minute".
Ghosting: Faint echoes of edges and features on walls, caused by frame vibration after sharp moves. Also called ringing. Reduce acceleration, check belts or use input shaping; see ghosting and ringing.
Gyroid: A wavy, continuous 3D infill pattern with equal strength in every direction. It reduces warping and flexes well in TPU, but is slower to print and slice than grid or cubic.

H

Heat break: The thin tube between the hot and cold zones of a hotend, designed to stop heat travelling upward.
Heat creep: Heat travelling up past the heat break and softening filament where it should still be solid, causing mid-print jams. Common with PLA in hot enclosures.
Heated bed: A temperature-controlled build platform that improves adhesion and reduces warping.
HMS (Health Management System): Bambu Lab's printer error and warning system. Each HMS code links to a wiki page that explains the fix.
Hotend: The assembly of heater block, heater, thermistor, nozzle and heat break that melts the filament.
HTPLA: High-temperature PLA: PLA made to be annealed after printing so it crystallises and handles much more heat than standard PLA. Heat resistance and shrinkage vary by brand.
HueForge: Desktop software for filament painting: it turns an image into a thin, layered print with color swaps at set heights, using each filament's transmission distance (TD) to predict how the layers blend.

I

IDEX: Independent dual extruders: two toolheads on separate carriages. Good for two-material prints with little waste and for printing two copies at once.
Infill: The sparse internal structure of a print, such as grid, cubic or gyroid, set as a percentage density.
Input shaping: A firmware feature that measures the frame's resonances and shapes moves to cancel them, allowing high acceleration without ringing. Also called resonance compensation. Supported by Klipper, Marlin 2.1.2 and later, Prusa and Bambu Lab firmware.
Ironing: A finishing pass where the hot nozzle runs over the top surface again with a tiny amount of flow to smooth it. Adds time and works best on flat tops.

J

Jerk: Marlin's classic setting for the instant speed change allowed at a corner, in mm/s. Higher is faster but rougher. Many setups use junction deviation (Marlin) or square corner velocity (Klipper) instead.
Junction deviation: Marlin's geometry-based alternative to jerk: it works out a safe corner speed from the corner's angle. The default is 0.013 mm.

K

Klipper: Open-source firmware that plans motion on a host computer (a Raspberry Pi or similar, or a built-in board on many commercial printers) and sends precisely timed steps to the printer's controller. Known for input shaping, pressure advance and macros.

L

Layer height: The thickness of each printed layer, typically 0.08–0.32 mm on a 0.4 mm nozzle. Thinner is smoother on slopes but slower; keep it under about 80% of the nozzle diameter.
Layer shifting: A failure where the print suddenly offsets in X or Y partway up, caused by skipped motor steps, a collision or a slipping belt.
Lightning infill: A branching infill that only grows where it's needed to hold up the top surface. Very fast and light, but adds almost no strength.
Linear advance: Marlin's implementation of pressure advance, set as a K factor with M900.
Load cell probing: Probing the bed with the nozzle itself by measuring the force when it touches, so there's no separate probe offset to tune. Prusa's MK4-family and CORE One printers use it, and Klipper supports it as a load cell probe.

M

Magic numbers: Layer heights that are whole multiples of the Z axis full step (screw lead ÷ motor steps per revolution). With an 8 mm-lead screw and a 1.8° motor that's 0.04 mm, so 0.12, 0.16, 0.20 and 0.24 mm are "magic". Printers with finer Z steps barely care.
Mainsail and Fluidd: The two most popular web interfaces for Klipper printers. Both talk to Klipper through the Moonraker API on the same host.
Marlin: Open-source firmware used on many consumer printers, configured before compiling. Recent versions support input shaping and linear advance.
Max volumetric speed: A filament-profile setting that caps flow in mm³/s; the slicer slows any move that would exceed it. Measure it with a volumetric speed test and set it 10–20% below the result.
Mesh leveling: Auto bed leveling that probes a grid of points and adjusts Z on the fly to follow any unevenness in the bed.
Minimum layer time: A cooling setting that slows the printer so each layer takes at least a set time (often 4–15 s), giving small layers time to harden.
MMU (Multi Material Unit): Prusa's filament selector. The current MMU3 switches between five filaments through one nozzle on Prusa MK-series printers.

N

Nozzle: The tip the molten plastic leaves through, usually 0.4 mm. Brass is standard; carbon- and glass-fibre filaments need hardened steel or another wear-resistant nozzle.
NTC: Negative temperature coefficient: the most common thermistor type, whose resistance falls as it heats up.

O

OctoPrint: Open-source web interface for controlling a printer over USB, usually running on a Raspberry Pi, with a large plugin ecosystem.
OpenSCAD: Free, open-source CAD software where you build models by writing code, which makes parametric parts easy. PrintPal's CAD Agent writes OpenSCAD from plain English. See the OpenSCAD tutorial.
OrcaSlicer: A free, open-source slicer forked from Bambu Studio (itself based on PrusaSlicer), known for built-in calibration tests and support for many printer brands.
Organic supports: Tree-style supports with smooth, rounded branches. The default tree style in Bambu Studio and OrcaSlicer, and PrusaSlicer's tree support since version 2.6.
Overhang: Part of a print that sticks out with nothing directly underneath. Up to about 45° from vertical prints without support on almost any printer; well-cooled printers often manage 50–60°.

P

PA-CF / PA-GF: Polyamide (nylon) filled with chopped carbon (CF) or glass (GF) fibres. Stiff and strong, but abrasive, so it needs a hardened nozzle, and like all nylon it must be dried.
PEEK: Polyether ether ketone: a high-performance engineering plastic that needs an industrial-class printer with a roughly 380–450 °C hotend and a heated chamber.
PEI: Polyetherimide, the most common build-surface coating. Smooth PEI gives glossy bottoms and strong grip; textured (powder-coated) PEI gives a matte texture and releases parts as it cools. PETG can bond too well to smooth PEI, so use textured PEI or a release agent such as glue stick.
Perimeter: The outline loops of each layer, also called walls. Two is the default in most slicers; 3–6 makes parts much stronger.
PETG: Polyethylene terephthalate glycol-modified. Tougher and more heat-resistant than PLA; prints at about 225–245 °C on a 70–85 °C bed with 30–50% fan. Strings more than PLA.
PID tuning: Calibrating the firmware's temperature control loop so the hotend or bed holds temperature without swinging. Re-run it after changing the heater, thermistor or hotend.
PLA: Polylactic acid. The easiest filament: prints at about 200–220 °C on a 55–65 °C bed with full cooling. Stiff but brittle, and it softens at about 55–60 °C, so keep PLA parts out of hot cars.
Pressure advance: A firmware feature that extrudes slightly ahead of acceleration and eases off before slowing down, compensating for pressure lag in the melt zone. Gives sharp corners without bulges or gaps. Bambu Lab calibrates it as flow dynamics; Marlin calls it linear advance.
Prime tower: A sacrificial tower printed beside multi-material prints, where the nozzle primes and stabilises flow after each filament change. Also called a purge tower, or a wipe tower in PrusaSlicer.
PTFE: Polytetrafluoroethylene (Teflon), used for low-friction Bowden tubes and hotend liners. PTFE-lined hotends should stay below about 240–250 °C, because PTFE starts to break down and release harmful fumes; use an all-metal hotend for hotter materials.
Purge: Filament extruded outside the part to clear the nozzle, for example before a print starts or after a color change.
PVA: Polyvinyl alcohol: a water-soluble support material, mostly paired with PLA. It dissolves in warm water but absorbs moisture quickly, so keep it sealed and dry.

Q

Quad gantry leveling (QGL): A Klipper routine for printers with four independently driven Z motors, such as the Voron 2.4. It probes near each corner and trams the gantry parallel to the bed before printing.

R

Raft: A thick, multi-layer base printed under the model. Rarely needed on modern PEI sheets, but still useful for uneven bottoms or very warp-prone materials.
Resin: Short for resin printing (SLA, MSLA, DLP), which cures liquid photopolymer with light. Far finer detail than FDM, but uncured resin is a skin irritant, so wear nitrile gloves and ventilate.
Retraction: Pulling filament back briefly before a travel move to stop oozing. Typical values are about 0.5–1 mm on direct drive and 2–6 mm on Bowden.
RFID filament tags: Small tags in spools that tell a compatible feeder the material, color and settings automatically. Bambu Lab's AMS reads them on Bambu Lab filament; some other brands use their own tags.
Ringing: Another name for ghosting.
Rotation distance: Klipper's replacement for steps per mm: how far an axis or extruder moves per full motor rotation, in mm. It equals full steps per rotation × microsteps ÷ steps per mm.

S

SCARA: Selective compliance articulated robot arm: a rare printer kinematics style that uses rotating arm joints instead of linear axes.
Scarf seam: A seam style that ramps the start and end of each outer wall up and down over a short distance so they overlap like a woodworking scarf joint, making the seam nearly invisible. Available in OrcaSlicer, Bambu Studio and PrusaSlicer 2.9 and later.
Seam: The point on each layer where the outer wall starts and ends, which lines up into a visible line. Slicers can align it, hide it in a corner, randomise it or let you paint it.
Skirt: A few loops printed around the part, not touching it, to prime the nozzle and check flow before the first layer.
SLA: Stereolithography: resin printing that cures each layer with a UV laser. Most consumer resin printers now use MSLA, which cures whole layers through an LCD mask.
Slicer: Software that turns a 3D model (STL, 3MF, OBJ or STEP) into the layer-by-layer G-code a printer follows. Examples: Bambu Studio, OrcaSlicer, PrusaSlicer and Cura.
Spool: The plastic or cardboard reel that filament comes on.
Square corner velocity: Klipper's cornering setting: the speed allowed through a 90° corner, 5 mm/s by default. Speeds for other angles are scaled from it.
STEP: A CAD exchange format (.step or .stp) that stores exact solid geometry instead of triangles. Use it to move models between CAD programs; several slicers can now import it directly.
Stepper: Stepper motor: the motor type used for printer axes and extruders. It moves in fixed steps, usually 200 per revolution (1.8°) or 400 (0.9°).
STL: The classic 3D printing mesh format: a list of triangles with no units, colors or materials. The name comes from stereolithography ("Standard Tessellation Language" is a later backronym). Still universal, but 3MF carries far more information.
Stringing: Thin hairs of plastic between separate parts of a print, caused by ooze during travel moves. Fixed with retraction, a lower temperature and dry filament.
Support: Sacrificial scaffolding printed under overhangs and removed afterwards. See the supports guide.
Support blocker / enforcer: Painted areas or modifier shapes that stop supports (blockers) or force them (enforcers) in specific places, instead of relying only on automatic detection.
Support interface: The dense top layers of a support that the model actually rests on. Two or three interface layers and a top Z distance of about one layer give clean undersides.

T

Thermal runaway: A firmware protection that shuts the heaters off when temperature stops responding as expected, for example when a thermistor falls out of the heater block. Never disable it.
Thermistor: A temperature-sensitive resistor that measures hotend or bed temperature.
Toolchanger: A printer that swaps between several complete toolheads or nozzles, each loaded with its own filament, so color changes take seconds and waste very little. Examples include the Prusa XL, Prusa CORE One INDX and Snapmaker U1.
TPU: Thermoplastic polyurethane: flexible, rubber-like filament, with 95A the most common hardness. Print it slowly at about 215–230 °C on a 40–60 °C bed. Direct drive makes it much easier, though harder grades can work through some Bowden setups.
Transmission distance (TD): HueForge's measure of filament translucency: the thickness at which a filament blocks about 95% of light. Low-TD filaments are opaque; high-TD filaments let lower layers show through.
Tree supports: Supports that grow branches from a few points on the bed up to the overhang. They use less material and leave smaller marks than normal supports, which suits figurines and organic shapes.

U

Under-extrusion: Not enough plastic being laid down, visible as gaps, thin walls or missing lines. Causes range from partial clogs and wet filament to asking for more flow than the hotend can melt.

V

Vase mode: A slicer mode that prints a single continuous spiralling wall with no infill or top, for vases and lampshades. Called spiral vase in Bambu Studio and OrcaSlicer and Spiralize Outer Contour in Cura.
Volumetric flow: The volume of plastic going through the nozzle per second (mm³/s): layer height × line width × speed. Usually the real speed limit on consumer printers.
Voron: A family of open-source DIY printer designs, most of them CoreXY, with a large community. Known for speed and quality, at the cost of a significant build.

W

Wall: Same as perimeter.
Warping: Corners of a print lifting off the bed as the plastic cools and shrinks. Worst with ABS, ASA, nylon and large flat parts.
Wipe tower: PrusaSlicer's name for a prime tower.

Z

Z-hop: Lifting the nozzle slightly during travel moves so it doesn't drag across the print. Helps on tall or curling parts, but adds time and can increase stringing.
Z-offset: The fine adjustment between where the printer thinks the nozzle touches the bed and where the first layer is actually printed. Sign conventions differ between firmware and slicers, so change it in small steps (0.01–0.02 mm) while watching the first layer.

Free PrintPal toolG-code ViewerSee what your slicer settings really do: open any G-code file layer by layerOpen tool

Your Cura profile has "Flow" set to 95%. What does that setting change?

The hotend's maximum mm³/s
The part cooling fan speed
How much plastic is extruded, as a multiplier

Cura's Flow is a percentage multiplier on extrusion, the same idea as flow ratio in Bambu Studio and OrcaSlicer or extrusion multiplier in PrusaSlicer. Volumetric flow in mm³/s is a different thing.

Frequently asked questions

What is the difference between FDM and FFF?

Nothing technical. Both describe melting plastic filament and laying it down layer by layer. FDM (fused deposition modeling) is a Stratasys trademark, so FFF (fused filament fabrication) became the open, generic name.

What does AMS mean in 3D printing?

AMS is Bambu Lab's Automatic Material System, a family of feeders that hold several spools and switch between them for multicolor prints or automatic refills. Other brands' equivalents include Prusa's MMU3 and Creality's CFS.

What is the difference between STL and 3MF?

STL stores only a mesh of triangles, with no units, colors or materials. 3MF packages the mesh together with units, colors, multiple parts and often slicer settings, which makes it the better format for multicolor and multi-part prints.

What is a bed slinger?

A printer whose bed moves back and forth along the Y axis, such as Ender-style, Prusa MK-series and Bambu Lab A1 printers. They are simple and affordable, but the moving bed limits acceleration compared with CoreXY machines.

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