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.