How to design your first 3D model
A first design from nothing to a saved file: choose a shape, give it real sizes, check it, and export it. About twenty minutes.
The fastest way to understand 3D design is to finish something small. Not a dragon. A name tag, a coaster, a phone stand, a cookie cutter — something with three or four decisions in it that you can hold by the end of the day.
1. Start with one shape
Every model, however complicated, is shapes added to and taken away from each other. Put one box on the plate. That is a complete design already: it has a size, it sits on the build surface, and it could be printed.
2. Give it numbers
Decide how wide, how deep and how tall it should be, in millimetres, and type those numbers in rather than dragging until it looks right. If the thing has a job — fitting a shelf, holding a pencil, covering a hole — measure the thing it has to fit and write that number down first.
Measure the real object with a ruler before you model anything that has to fit it. Almost every disappointing first print is a guessed measurement.
3. Add a second shape, and join them
Two shapes that merely touch on screen print as two loose objects. Joining them runs a real geometric union so they become one solid. A good design tool lets you take that join apart again afterwards, so committing to it costs nothing.
4. Take material away
Holes are made by taking one shape away from another rather than by drawing a hole. Put a cylinder where the hole should be, then subtract it. If the hole has to fit something — a screw, a peg, a lace — make it slightly larger than that thing. How much larger is its own subject.
5. Check, then export
Before you save, look at what the tool can tell you: is it one connected piece, is anything below the plate, is anything larger than the design limit. Then export. Prefer 3MF, which keeps millimetres and colour; STL is fine and universal but records neither.
What to expect from the first print
It will probably be slightly smaller than you modelled, slightly rougher than you imagined, and completely satisfying anyway. Measure it with a ruler or callipers, compare it to your model, and change the model. That loop — design, print, measure, revise — is the actual skill.
Do it, don't just read it
This pairs with lessons inside the Studio, where the checkpoints tick because the design really has that property, and un-tick if you undo the work:
- Lesson 1 — First Block
- Lesson 4 — Ready to Print
Read next
Starting out
What is 3D printing?
How a 3D printer turns a design on a screen into an object you can hold — explained for children, parents and teachers, with no jargon.
Designing well
How thin can a 3D printed wall be?
Why hollow models need a minimum wall thickness, how to choose one, and what happens when a wall is thinner than the printer's nozzle.
Designing well
Clearance and tolerance: making parts that actually fit
Why a 10 mm peg will not go into a 10 mm hole, how much gap to leave, and how to work out the right number for your own printer.