Home › Blog · For kids and parents · 14 November 2026
How does a 3D printer work?
A normal printer puts ink on paper. A 3D printer builds a real object you can pick up. Here is how it does it.
Think of a glue gun on a robot arm
The most common kind of 3D printer works a bit like a very careful hot glue gun. It melts a thin plastic string, called filament, and squeezes it out through a tiny nozzle. A machine moves the nozzle around to draw a shape.
Then it moves up a tiny bit and draws the next shape on top. And again. And again. Hundreds of thin layers stack up until the object is finished.
Step 1: design it
Every print starts as a 3D model on a computer. At Robokids, children make theirs in Tinkercad by dragging shapes together, stretching them and cutting holes in them.
Step 2: slice it
The printer cannot understand a 3D model directly. A program called a slicer cuts the model into flat layers, like slicing a loaf of bread, and writes instructions for every single one.
Step 3: print it
The printer heats its nozzle to around 200 degrees Celsius, which is hotter than an oven baking a cake. The melted plastic cools and hardens in seconds, so each new layer has something solid to sit on.
Each layer is very thin, often about a fifth of a millimetre. That is why printing takes patience. A small keyring can take around half an hour, and a bigger model can take many hours.
What is the plastic made of?
Most classroom printers use a plastic called PLA. It is made from plants such as corn, and it melts at a lower temperature than many other plastics, which makes it a good choice for beginners.
Try this at home
Stack coins or building bricks to make a tower, a pyramid, then a staircase. You are doing exactly what a 3D printer does: building a shape one layer at a time. Which shapes are easy? Which ones fall over? Designers have to think about that too.