The Perfect Match? Using 3D Printing and LEGO for Better Prototyping


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A diagram showing common physical prototyping techniques occupying a spectrum of fidelity, reconfigurability and skill level.  See more on the clay modeling image here.

While 3D printing has become a force in on-demand product manufacturing and a catalyst for creating many different functional objects, the technology was created to allow engineers to create rapid prototypes—with some being more perfect than others. In ‘Accelerating product prototyping through hybrid methods: Coupling 3D printing and LEGO,’ authors David Mathias, Chris Snider, Ben Hicks, and Charlie Ranscomb take on a modular approach to fabrication and prototyping.

For this project, the authors designed six different 3D shapes with a ‘continuum of hypothetical brick sizes.’ And while it’s hard not to think of LEGOS without getting inspired just due to the creative fun factor associated with the colorful building blocks, the researchers here were serious about studying the benefits of such material and technological collaboration—yielding a staggering reduction in fabrication time of up to 45 percent, with ‘reconfigurability of 57 percent at the optimum.’ Trailing behind also, are all the classic benefits of 3D printing: speed in production, affordability, savings in cost of materials, and rapid development.

“Prototyping is an essential part of the product development process and it is widely accepted that increased prototyping – both physical and virtual – leads to improved products,” state the authors in their study.

They outline the benefits of prototyping as follows:

  • Comprehensive exploration of a design space
  • Opportunity to solve design problems
  • Supplementation of designers’ mental models
  • Discovery of unexpected phenomena
  • Offering boundary objects for communication

The ‘trade off’ between time and quality of work in prototyping is discussed at length, but the authors also remind us of another benefit in this type of production as designers can engage with their designs more physically, ‘designing by hand.’

Aside from 3D printed structures, other materials often used in prototyping are foam, cardboard, and clay—which can be a high-fidelity endeavor. The authors remind us that no matter what form the prototype takes, if it is the materials are easy to use and the technique promotes expediency, more iterations can be made in striving to create a final product.

Benefits of adding LEGO blocks to the 3D printing quotient include:

  • Straightforward modeling
  • No health or safety precautions required
  • Aside from the obvious materials, no other tools are required

“Coupling low cost 3D printing and LEGO® introduces a level of fidelity unachievable by LEGO® alone while maintaining the flexibility and reconfigurability of a construction kit. It affords rapid ideation and modification with a physical prototype to avoid breaking user studies or creative episodes,” stated the authors.

Computer simulation was used to assess the viability of the project, and then it was put into action 3D printing a video controller for a case study meant to further demonstrate the advantages of such a coupling for the building of prototypes. Typical primitive shapes were chosen for the samples, in the form of:

These primitives consisted of:

  • Cube
  • Cylinder
  • Cone
  • Sphere
  • Tetrahedron
  • Triangular Prism

The primitive shapes used in the simulations. From L to R: Cube, Cylinder, Triangular Prism, Tetrahedron, Cone, and Sphere

“The volume of the objects was varied over a range of 1 × 103–8 × 103 mm3. These volumes were used as they are within the bounds of feasibility for most commercially available desktop low cost 3D printers–such as the Ultimaker 3 (9.42 × 103 mm3 (Ultimaker, 2018)) and Makerbot Replicator + (9.45 × 103 mm3 (MakerBot Industries, 2018)).”

“The simulations were stepped 50 times over this volume range. This was then repeated for each of the object shapes, and each of the sizes of brick.”

Sizes of bricks were described as follows:

“The initial brick size was LEGO with dimensions of 8 × 8 × 3.2 mm. For these simulations, a pool of standard bricks could be used to reduce the overall brick count (see Section 3.3.2). Smaller and larger bricks were considered either side of LEGO, these include NANO (4 × 4 × 3.2 mm) and DUPLO (16 × 16 × 19.2 mm). The use of different sizes of brick affords different levels of fidelity, with the expectation that the smaller bricks will allow a better approximation of more complex geometry.”

Comparison of the three sizes of construction kit brick

The researchers noted substantial time differences in 3D printing time for the three sets of bricks—with NANO bricks offering slower time, LEGOs offering the ‘greatest improvement in fabrication time’ and DUPLO bricks turning in a worse performance than the LEGO bricks. Reusability (the amount of materials that can be transferred to another prototyping design experience) was best for NANO bricks; worst for DUPLO—leaving the authors to state the use of smaller bricks would be best for users with reusability in mind.

Overall, however, the modular dynamic means greater ease for users as there is substantial latitude in being able to physically make changes to the designs. Whether they are inserting or removing LEGOS or refining the 3D printed components, prototyping can be improved on numerous levels—offering more expansive opportunity for design by connecting the concept process to that of actual, true physical, fabrication.

“This approach to creating looks-like prototypes of user-driven products is form dependent. Consequently, there could be better approaches using different prototyping methods to reduce the fabrication time and costs for particular designs,” concluded the researchers.

“Further work is required to realize the physical practicalities of producing prototypes using this hybrid approach, including optimizing brick layout for part strength and ease of construction, and to generate 3D printable surface pieces that attach to the LEGO bricks. As the resultant prototype is modular it would need to be constructed in such a way that it could be strong enough to withstand designer/user interaction without falling apart yet be easy enough to dismantle or reconfigure.”

A plot showing the total fabrication time against the object volume for the three brick sizes, a reference line for solely printing the object is included

3D printing and LEGOS are a natural match for users creating projects around the world, not only due to the plastics involved but because they are both centered around building and creating objects that may often also incorporate electronics and innovative controllers, from a motorized Go-Kart to kits requiring 3D printing of almost 400 parts—or 3D printers actually built with LEGOS.

The library of standard LEGO® bricks

[Source / Image: ‘Accelerating product prototyping through hybrid methods: Coupling 3D printing and LEGO’]

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