# 3.5: Material

There are two ways for defining materials in Karamba3D: Either select a material by name from a list of materials (see section [3.4.2](/3-in-depth-component-reference/3.4-material/3.4.2-material-selection.md)) or set mechanical material properties manually (see below).

{% hint style="info" %}
The Appendix (see section [A.2.1](/appendix/a.4-background-information/a.4.1-basic-properties-of-materials.md)) contains additional information on mechanical properties of materials.
{% endhint %}

Materials constitute a property of cross sections. There are two ways of attaching materials to cross sections:

1. In order to directly assign a material to a cross section, plug it into the corresponding cross section creation component. This is overridden by indirect material definitions via the **“Assemble”** component as described below.
2. Materials (like cross sections) may be plugged into the **“Assemble”** component. They know about the elements (or element sets) they apply to by their **“Elems|Ids”** property: This is a list of strings containing element identifiers (see section [3.1.6](/3-in-depth-component-reference/3.1-model/3.1.6-create-linear-element/3.1.6-line-to-beam.md)) or regular expressions that match a group of element identifiers (element-ids). Upon assembly each element-id is compared to all **“Elems|Ids”** entries of a material. In case they match the material is attached to the element. An empty string – which is the default value – signifies that the material shall be applied to all elements.


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