What is 3D printing?
3D printing builds physical objects by adding material one thin layer at a time, following instructions from a digital 3D model. Each layer is a flat cross-section of the object — stack a few hundred of them and you get the real thing.
That's why engineers call it additive manufacturing. Most traditional workshop methods are subtractive — you start with a block of material and cut, drill, or carve away everything that isn't your part. 3D printing runs in the opposite direction: it starts with nothing and adds only the material your part needs.
This one trick — building in layers — is what gives 3D printing its superpowers. Complexity is nearly free: internal channels, lattices, and organic curves that are impossible to machine cost no more effort than a plain cube. Iteration is fast and cheap: print version one overnight, spot the flaw, print version two tomorrow. And one-offs are viable: with no moulds or tooling, a single custom part costs only its material and machine time.
Every 3D printing technology you'll ever meet — whether it melts plastic, cures liquid resin with light, or fuses powder — is just a different answer to the same question: how do we make one layer, and stick it to the layer below?
Reality check
3D printing is not magic. Prints take hours, not minutes; surfaces show faint layer lines; every machine has a maximum build size; and failed prints are a normal part of the process — even for experts. Knowing this now saves frustration later.
From model to object
Every print, on every machine, follows the same four-step pipeline. The first two steps happen on a computer; the last two happen in the real world. Learn this once and you've learned all of 3D printing — the technology guides just fill in the details.
STEP 1
Model
STEP 2
Slice
STEP 3
STEP 4
Post-process
Get a 3D model digital
Everything starts with a digital 3D model — a file describing your object's shape. You can design one, download one, or 3D-scan a real object (chapter 04 covers all three routes). Whatever the source, it ends up as a mesh file — usually .STL or .3MF — a "skin" of tiny triangles describing the object's surface.
Slice it into layers digital
A program called a slicer cuts the model into hundreds of horizontal layers and writes step-by-step machine instructions. This is where the big decisions live: layer height (finer = smoother but slower), supports (scaffolding for overhangs), and orientation (which way up it prints) — all explained in chapter 03.
Print it, layer by layer physical
The printer follows the sliced instructions, building each layer and bonding it to the one below. A keyring-sized part might take under an hour; a palm-sized part typically runs 3–8 hours; large or very fine prints can run for days. The machine works unattended — nobody stands there watching it.
Post-process the part physical
A part isn't finished when the printer stops. Almost every print needs some finishing work: snapping off support material at minimum, and depending on the technology, washing and UV-curing (resin), removing loose powder (SLS), or optional sanding and painting. Budget time for it — it's part of the process, not an extra.
Who does what at UNSW?
Bring a model to the 3DP Hub and our team handles steps 2 and 3 for you — no training needed. Prefer to drive the machine yourself? Earn the DIY 3D Printing Badge for hands-on access to dedicated printers.
Six ideas that explain almost everything
These apply to every 3D printing technology, and they're behind nearly every question you'll ever have about why a print looks, behaves, or fails the way it does.
IDEA № 1
Layers set the resolution
Layer height controls vertical detail — typically 0.1–0.3 mm. Thinner layers look smoother but multiply print time: halving the layer height roughly doubles the hours. Faint layer lines are always visible up close; they're the fingerprint of the process.
IDEA № 2
Every layer needs a foundation
Each layer must rest on something — usually the layer below. Shapes that lean out over empty space — overhangs — have no foundation, so every technology needs a plan for them. The most common one: printing supports, disposable scaffolding you remove afterwards, which costs material, time, and surface quality. A few technologies hold layers up other ways instead. Either way, overhangs are never free — good designs keep them in mind.
IDEA № 3
Complexity is free — size is not
Printers don't care how complicated a shape is; they care how much material it uses and how tall it stands. An ornate part takes about as long as a plain one of the same size — but double a part's dimensions and its volume (and print time, and cost) grows roughly eight-fold. This is why experienced makers prototype small and scale up only when the design is proven.
IDEA № 4
Orientation changes everything
Which way up a part prints decides where supports go, which surfaces come out clean, how fine details resolve — and usually how strong it is. Because a part is a stack of bonded layers, it tends to split between layers, like wood along its grain (how much varies by technology). Orient parts so loads run across the layers, not between them, and put the faces you care about where supports aren't.
IDEA № 5
Models must be watertight
The slicer needs a model whose surface is completely sealed — called watertight (or manifold). Gaps, holes, and zero-thickness walls confuse it, because "inside" and "outside" stop meaning anything. Downloaded and scanned models often need a quick automatic repair pass before they'll slice cleanly.
IDEA № 6
Leave room for reality
Printers aren't perfectly precise, and plastic shrinks slightly as it cools. Expect roughly ±0.2–0.5 mm on a typical print; holes come out a touch small. Parts that fit together need a designed-in clearance gap — about 0.2 mm for snug, 0.4 mm for easy. When fit matters, print a small test piece first.
Three ways to get a 3D model
You don't need to be a designer to print. Pick whichever route matches your project — most beginners start with a download.
Download one Easiest
Free libraries like Printables, MakerWorld, and Thingiverse host millions of ready-to-print models shared by makers worldwide — brackets, enclosures, replacement parts, and plenty of fun. Also a great way to learn by studying how experienced designers model for printing.
Design your own Most powerful
Model exactly what you need in CAD software — a skill that also unlocks laser cutting and CNC machining. Any program that exports an .STL works with every printer on campus. Which software to choose and where to learn it is a guide of its own: read the CAD Starter Guide.
3D scan a real object For replicas
Our 3D scanners capture a physical object's surface and turn it into a printable mesh — handy for replicating, repairing, or remixing real things. Scans usually need a clean-up pass (smoothing, hole-filling, scale check) before printing. Learn to 3D scan.
Before you print — a two-minute check
Whatever the source, confirm the model is the right size (downloaded files are often scaled oddly) and watertight (idea № 5). A two-minute check beats a six-hour failed print.
One process, many technologies
Every 3D printer follows the same four-step pipeline — they differ only in how each layer is made. That's the whole difference between the technology families. Each has its own guide with the practical detail; here's the thirty-second version.
Melted plastic, drawn in lines
Like a precise hot-glue gun: molten filament traced layer by layer. Cheapest, most available, and where every beginner should start.
Liquid resin, cured by light
UV light hardens each layer in a vat of liquid resin. Exceptional fine detail and smooth surfaces; needs washing and curing afterwards.
Specialist processes
Laser-fused nylon powder, continuous carbon-fibre reinforcement, even ceramic clay — for projects with material or structural needs the mainstream can't meet.
Quick answers
The things everyone wonders and nobody wants to ask.
Do I need to learn CAD before I can print?
No. Download a ready-made model and submit it to the 3DP Hub — our team handles slicing and printing. CAD is worth learning eventually, but it is not the price of admission.
How long does a print actually take?
Machine time runs from under an hour (keyring-sized) to days (large or very fine). Hub jobs also queue behind other people's work — typically 1–3 business days for standard FDM, longer near end-of-term deadlines. The lesson: never leave printing to the last minute.
How strong are printed parts?
Strong enough for most prototypes, jigs, brackets, and enclosures — but weaker than injection-moulded or machined parts in the same material, and weakest between layers (idea № 4). If your part carries a real structural load, come talk to us.
What can go wrong?
Plenty, and that's normal: parts detach from the build plate, warp as they cool, fail at an unsupported overhang, or turn to "spaghetti" when a layer slips. Even experts see failures — the difference is they budget time for a reprint. Plan for at least one do-over on anything that matters.
What does it cost?
It depends on material, technology, and size — small FDM parts are usually only a few dollars. See the pricing schedule for current rates; some courses prepay for coursework prints.