3D printing technology

Types of 3d prototyping technologies

The 3D prototyping technologies can be classified in two main groups: additive, by adding material or subtractive, by removing material with a tool.
It is also possible to create a 3D model in a crystal with a laser, but this technique, despite the interaction with a physical material, can be assigned more to a rendition solution because it allows only visual inspection and not full functionality.

Additive printing

The technology that is more convenient is to weld material by hot extrusion which uses a principle similar to that of the hot glue gun. It is also called FFF Fused Filament Fabrication. There are other possibilities such as laser sintering for metals, but they are more costly and complicated.


Material more used are:

  • ABS, the same material as Lego bricks
  • PLA, a polymer based on vegetal amid, derived from maise.
  • Nylon
  • Elastic polymers

The most widely used plastic material (ABS or PLA) costs about 30 Euros per kilo.
The main technological differences between ABS and PLA are:

  • Different melting temperature
  • Biodegradability (highest in the PLA)

Further considerations regarding the use of these two material and what is better, can be found here.


An extruder heats the plastic material fed in filament form and deposits it in thin wires to obtain the final object, via a positioning system with three spatial axes, similar to a numerical control system. The path of the extruder is obtained from a 3D mathematical model, using appropriate algorithms that are also able to generate the supports for the cantilevered parts and replace any full frame with strong and light structures.

Subtractive printing

The limits of this technique well known in the mechanical industry are related to the realization of complex hollow elements that require dividing the realization of the object into multiple parts.


It is also possible to work wood and metals such as aluminium.


In subtractive printing the extruder is replaced by a rotary tool-holder head also called milling cutter, capable of removing material from an initial solid block, by repeated layers.


The choice of technology for the production of accessories for Thymio (with or without supporting material, etc.) should be based mainly on the economy and simplicity of use. As part of a laboratory prototype, for particular processes, the additive technology can be integrated for the removal of material for refinements, adopting a printer that allows both technologies.

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