Setting an icon from the tools panel to a button in the custom UI panel in Blender

To set an icon to a button when creating the custom user UI panel in Blender, we look for the text identifier of the desired icon (usually using the built-in Icon Viewer add-on) and set its value to the "icon" parameter when binding the desired operator to the button. However, the icons used in the tools panel are not existed in the common Blender icons list.

Read more: https://b3d.interplanety.org/en/setting-an-icon-from-the-tools-panel-to-a-button-in-the-custom-ui-panel-in-blender/