Introduction to 3D Printing

What is it?

3D Printing – a process to produce a physical object from a three-dimensional digital model. This is an additive process, usually building up from many thin layers of a material.

Finch has two Taz 4 printers, and will soon be receiving two Prusa i3 Mk3 printers. Both are reliable workhorse printers – they’ll be printing hundreds of student models over the school year.

There are many types of 3D printer (powder, resin, metal, laser melting, and more) but the most common type is called a ‘Fused Deposition Modeling’ (FDM) printer.

In the FDM process:
A filament of plastic material (a) is fed from a roll
To an extruder (b) that melts it and pushes it through a nozzle,
Depositing it, layer by layer, into the desired shape. (c)
Overhanging parts of the shape need temporary support structures. (d)
A moving bed (e) lowers (or the head raises) after each layer is deposited.

Why Does it Matter?

There are limits to the printing process. As a designer you must be aware of these – or else your design might be un-printable!

    • Nozzle Size: The printer nozzle limits how small any feature of the design can be.
      If a wall is less than the thickness of the nozzle (0.4 mm typically), it won’t be printed!
    • Bed Size: If your design is too large it won’t fit! A design can be split into multiple parts for printing, but then you’ll need to glue it back together.
    • Overhangs: Overhanging parts need temporary supports, usually made from the same material. Supports can be hard to remove, and there are marks left behind. Try to avoid needing too many supports, especially in hard-to-remove places.
    • Time: 3D printing is not a fast process. We usually run larger 3D print jobs overnight. The longest print job (making eight pistons for the Moo Brew machine) took over 52 hours!

Anisotropy – Not All Directions are Equal

3D printing builds up layer by layer.
Printed parts are very strong in two directions, and weak in the third.
(This is called anisotropy)

Think about how your part should be oriented for printing to make it strong.
Keep this in mind as you design:

  • Tall and thin parts are weak, can you print them lying down?
  • Will it need supports in that orientation?

This simple hook design can be 3D printed in many different orientations.

Which orientation will print the best?
Is it worth cutting the model into two pieces?


It’s a small model – let’s find out!
The hook is printed in ABS plastic in several orientations.

Week 3 Homework: The 100 mm 3D Printing Challenge

You have begun to learn how to use Fusion 360.
If you get stuck, look at the tutorials and other reference information here.

This week’s homework is to design something of your own that can be 3D printed. Your only restriction is: the combined length + width + height of your model must be less than 100 mm.

You can check this by right-clicking (Mac: two-finger-clicking) on the topmost element in the browser, and looking at the Bounding Box area.

Some suggestions, if you get creatively stuck:

  • Jewellery: a ring, a pendant, earrings
  • Pair of dice
  • Spinning top
  • Keychain
  • Hook, for your bag or for the wall
  • Bookmark
  • Easter Island head?

Submit your designs, and we’ll 3D print them!

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