Blender is great for creating LEGO and other plastic brick models. This post will show how to create solid plastic material in the Blender Cycles and Eevee render engines.
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Being the most popular, LEGO bricks come in various types of plastic mixtures – each giving them a unique surface appearance. The most common plastic material is the plain, solid material. When looking at a solid plastic brick, it is made from ABS plastic, is completely homogenous in colour, mostly smooth and has a nice shine to it.
Choosing a rendering engine in Blender
The latest version of Blender (2.8 (Jul 2019)) has two rendering engines, namely Cycles and Eevee – each with their own strengths and weaknesses. Cycles is more comprehensive and will give beautiful results. Eevee is by far the fastest and even capable of real-time rendering, but the quality is often cartoonish and unrealistic for still renders.
Working with materials in Blender
Each object in Blender can have its own material and the same material can be assigned to multiple objects. Both Cycles and Eevee use similar material settings. New material settings can be duplicated from an existing material. After modelling or importing an object (in this case a LEGO brick) the object may or may not already have a material assigned to it. To assign a material to an object in Blender, select the object, go to the Materials tab in the Properties panel and click on the Add new material button.
After giving the new material a name, the material properties can be assigned in the Shader Editor. If the object already has a material assigned to it, its properties can also be changed in the Shader Editor.
By default, Blender 2.8 and newer will have Workbench selected as the default ‘render engine’. Now is the time to either choose the Cycles or Eevee rendering engine. The render engine can be selected from the Render tab in the Properties panel.
After the render engine is selected, the node setup and other settings in the following two sections can be used to create a realistic solid plastic brick material.
Creating a solid plastic material in Blender Cycles
After the object has a material assigned to it, it can be tweaked to look like the material it needs to be. For a quick reference, here is the node setup for a realistic-looking solid plastic brick material using Cycles:
In this node setup, a Diffuse BSDF and Glossy BSDF node are mixed using a Mix Shader (all three nodes available from the Shaders section). The final colour of the plastic brick is selected by using the Color setting in the Diffuse node. Also see the plastic brick solid colour palette for the colours I use.
The Glossy node’s Color setting needs to be completely white and the Roughness needs to be set to 0.050.
The factor of the Mix Shader is either set to 0.050 or by using a Fresnel set to 1.460.
To see the material effect in the Viewport, make sure to change the Viewport Shading from Look Dev to Rendered.
Duplicating materials for different colours
After the first solid plastic brick colour has been set, it is easy to duplicate the material and simply change the name and Diffuse Colour setting.
A material can be duplicated by clicking on the New Material icon. The material name and Diffuse Color setting can be changed as desired.
By changing the material Link from Data to Object, linked objects can be assigned different materials.
The created materials can now be used on new objects by choosing them from the material drop-down list. Materials that are assigned to objects will be saved with the .blend file, but unused materials will be removed if the file is reopened.
Creating a solid plastic material in Blender Eevee
Although Cycles will create a much more realistic render, Eevee will render much faster. To create a solid plastic brick material using Eevee, only the Principled BSDF node is required. This node will control the roughness, specular and index of refraction (IOR) of the material. For a quick reference, here is the node setup for a realistic-looking solid plastic brick material using Eevee:
As with Cycles, the Base Color will set the main colour of the brick. Once again, see the plastic brick solid colour palette for the colours I use. Although these settings will vary on your specific scene, the Specular value generally needs to be quite high (close to a value of 1.0) and the Roughness needs to be decreased to about 0.0. Realism of Eevee renders will be much dependant of the Render settings, which do not fall in the scope of this post.
Interestingly, by using this node setup and changing the render engine back to Cycles, a very realistic effect can also be obtained.