Follow the steps below…
Because large applications might have a large number of 3D models to choose from, models are stored in a small hierarchy of their own.
For example, a light-switch may be found under Electrical / Switches / Household Wall Mount / Single.
There are always four category entries for each 3D model.
If the list of skins contains items under Item Specific Skins, you should use those - they are specifically designed to make your 3D model look the best it can be.
Otherwise, there are several built-in skins that apply to every model. These are useful when you don't have the time, resources or interest to build your own skins.
This is an optional step, as only some skins allow you to change the colour.
This option lets you nominate the dominant colour for your asset. When your skin is designed to work with the colour picker, it allows you to change the colour that your asset is painted. It allows you to match your 3D models to your chosen manufacturers colour, or when your plant colour-codes assets by their application (ie. light-blue for air, dark-blue for water, yellow for hydraulics etc.).