3D Printing Glossary

FDM is the most common and most affordable method of 3D printing - and it's the technology this site focuses on. It works by feeding a spool of plastic filament into a heated nozzle, which melts it and deposits it in thin layers on a build plate. Each layer fuses to the one below it, and over dozens or hundreds of layers, a 3D object takes shape. Think of it like a very precise, very slow hot glue gun that follows a digital blueprint. The results are solid, functional parts that can be made from a wide variety of materials. Most home printers you'll find on the market today use FDM.

Filament is the raw material an FDM printer uses - the equivalent of ink in a regular printer. It comes as a long, thin strand of plastic wound onto a spool, and feeds into the printer's extruder where it gets melted and deposited. Different filament types have very different properties: PLA is easy to print and costs around $15–20 per spool, making it the go-to for beginners. PETG is tougher and handles moisture better. TPU is flexible. ASA handles UV and outdoor conditions. Choosing the right filament for the job matters as much as choosing the right printer. Most spools weigh 1 kg and last a long time for typical hobby use.

The build plate - also called the print bed - is the flat surface the printer deposits filament onto. It's where your print literally starts, layer by layer. The size of the build plate determines the maximum size of an object you can print in one go. A common standard is 256 × 256 × 256 mm, which fits most everyday prints with room to spare. Better build plates are flexible (so you can pop prints off easily), heated (which helps the first layer stick and prevents warping), and textured (for better adhesion). The build plate is one of the most important parts of a printer - a bad one will cause your prints to lift, warp, or fail entirely.

A bed slinger is a printer design where the build plate moves back and forth along the Y axis (toward and away from you) while the extruder moves side to side (X axis) and up and down (Z axis). It's the traditional layout for affordable printers and it works - but it has trade-offs. Because the print is being moved around while it's being built, taller prints can wobble slightly, which reduces quality. The constant back-and-forth motion of a heavy plate also limits how fast you can go without causing vibrations that show up as ripples on your print. The big upside: bed slingers are simpler to build, cheaper to buy, and easier to repair. Most budget printers use this design.

CoreXY is a printer motion system where the build plate only moves vertically (Z axis, straight up and down), while the extruder handles all the horizontal movement (X and Y). Two motors work together through a belt system to move the print head in any direction across the flat plane. Because the actual print never gets shaken around, CoreXY printers produce sharper, cleaner results - especially on taller objects. The stationary-plate design also allows for much faster print speeds since you're only moving the lightweight extruder rather than the heavy build plate. Almost all high-performance printers - including the Bambu Lab lineup - use CoreXY. The trade-off is a more complex internal mechanism that can be harder to work on.

The extruder is the system responsible for pushing filament into the hotend, melting it, and depositing it precisely onto the build plate. It has two main components: the cold end (a motor and drive gears that grip and feed the filament) and the hot end (the heated block and nozzle where filament actually melts). On a CoreXY printer, the extruder moves along the X and Y axes over the stationary bed. On a bed slinger, it moves along the X and Z axes. On a delta printer, it moves in all directions while the bed stays completely still. There are two main styles: direct drive (where the cold end sits right on top of the hot end - better for flexible filaments) and Bowden (where the cold end sits elsewhere and a tube routes filament to the hot end - lighter, faster, but less flexible with certain materials).

A delta printer is a distinctly different design where the build plate never moves at all - the extruder does all the work. Three vertical rails sit at the corners of a triangular frame, and three arms connect the rails to the print head. All three arms work together to position the extruder precisely in three-dimensional space. Because nothing heavy is being moved back and forth, delta printers can reach very high speeds with excellent print quality. They also tend to have tall, cylindrical build volumes - great for printing tall, narrow objects. The downside is that delta printers are more expensive to build, trickier to calibrate, and less common, which means fewer tutorials and community resources if something goes wrong. The Prusa Pro HT90 is a delta printer.

The nozzle is the small metal tip at the very end of the hotend - the final point where melted filament exits the printer and gets placed onto the print. The size of the nozzle's opening (its diameter) directly controls how thick each line of plastic is. The standard is 0.4 mm, which is a balance between speed and detail. Larger nozzles (0.6 mm, 0.8 mm) print faster but with less detail - good for large structural parts. Smaller nozzles (0.2 mm) print slower but with finer detail - good for miniatures or intricate designs. The material the nozzle is made from also matters: brass nozzles are standard and work for most filaments, but they wear down quickly with abrasive materials like carbon fiber composites. Hardened steel nozzles last much longer with tough materials like PLA-CF but conduct heat slightly less efficiently.

A slicer is the software that takes your 3D model and prepares it for printing. It works by cutting (or "slicing") the model into hundreds or thousands of horizontal layers - this is an FDM-only step, because FDM printers build objects one layer at a time. Once sliced, the software generates a file called G-code: a set of precise instructions that tells the printer exactly what to do - where to move, how fast to move, when to extrude filament, when to retract it, and how to home itself at the start of a print. Everything from layer height to infill to wall count is configured inside the slicer. Popular slicers include Bambu Studio, OrcaSlicer, and PrusaSlicer.

Layer height is how thick each individual layer of your print is - it's one of the most important settings in your slicer because it directly controls the balance between print quality and print speed. A smaller layer height (like 0.1 mm) means more layers, finer detail, and smoother surfaces - but significantly longer print times. A larger layer height (like 0.3 mm) prints much faster but with more visible layer lines and slightly less surface detail. The standard for most prints is 0.2 mm, which gives you a solid middle ground. Layer height is also limited by your nozzle size - as a rule of thumb, don't go above 75–80% of your nozzle diameter.

Infill is the internal structure printed inside a 3D model to give it strength and something to build on. Without infill, most models would be completely hollow - and while a hollow print might hold its shape on the outside, it would be fragile and the top layers would have nothing to bridge across. The slicer automatically generates infill based on two settings you control: the infill percentage (how much of the interior is filled) and the infill pattern (what shape the internal structure takes). Infill uses real filament, so the more infill you add, the heavier, stronger, and more material-intensive your print becomes.

Infill percentage controls how much of the inside of your model is filled with material. A setting of 20% means 20% of the interior volume is solid filament; the rest is air. The standard default in most slicers is around 15%, which is enough for most decorative or low-stress prints. Here's the thing most beginners don't know: you can often go much lower - even down to 5–10% - and save a significant amount of filament and time without noticeably weakening the part. For functional parts that need to handle real stress, you'd go higher - 40% or more. But for everyday prints, reducing infill is one of the easiest ways to make your filament last longer.

Infill pattern is the geometric shape the slicer uses to fill the inside of your model. Different patterns have very different properties. Some prioritize strength - like Cubic or Gyroid, which distribute stress evenly in all directions and are great for functional parts. Some prioritize speed and filament savings - like Lines or Lightning, which use minimal material and print fast but offer less structural strength. Some are all-rounders - like Honeycomb, which balances strength and efficiency. And some are just not worth using for most purposes. Gyroid is widely considered one of the best all-around patterns: it's strong, isotropic (same strength in all directions), and doesn't have long straight runs that can cause resonance issues at high speeds.

Walls (sometimes called perimeters or shells) are the number of times your printer traces the outer edge of your model before filling in the inside with infill. Each wall is one pass of the nozzle, and since the standard nozzle is 0.4 mm, each wall adds 0.4 mm of thickness to the outer shell of your print: 1 wall = 0.4 mm, 2 walls = 0.8 mm, 3 walls = 1.2 mm. The default in most slicers is 2 walls, which works fine for decorative parts. For anything that needs real strength - functional brackets, structural parts, anything that takes load - increasing to 3 or 4 walls makes a significant difference. Crucially, adding walls is more efficient than adding infill: it costs less time and filament but delivers better real-world strength, because most stress on a print is applied at the surface, not the core.

PLA (Polylactic Acid) is the most commonly used 3D printing filament and is made from plant-based materials like corn starch or sugarcane, which makes it biodegradable under industrial conditions. It prints at relatively low temperatures, usually around 200–240°C, and doesn't require a heated bed, although 50–60°C helps with adhesion and reduces warping. PLA is known for being easy to print because it has low shrinkage, minimal warping, and strong layer adhesion, making it ideal for beginners and general-purpose models. However, it is more brittle than materials like PETG or ABS, and it starts to soften at around 55–60°C, so it's not suitable for high-heat or high-impact functional parts. For decorative prints, prototypes, and lightweight models, PLA is usually the default choice because it balances print quality, speed, and reliability with very little tuning required.