To Add a Tool

In the Customize dialog ( File > Settings > Configuration > Customize ) , click the Tools tab.
Expand the User Tools section.
Expand the open DGN file.
Select the toolbox into which you want to add the tool.
Do one of the following:

Click the New Tool icon.

or
Right-click the toolbox and select New Tool from the pop-up menu.

A new tool appears with the name "New Tool."
Type a name for the new tool.

Once you add custom tools to the open DGN file (represented by the blue V8 icon), they appear in the left pane on the Tools tab in the Customize dialog. You can name your tools and organize them by moving them up or down within a toolbox or by moving them into another toolbox. The tools in the open DGN file also can be copied, deleted, renamed, and have properties added to them.

Tools cannot be copied or moved from the open DGN file into other DGN libraries or into the Application Tools (represented by the gray V8 icons). However, the tools from any DGN library or from the Application Tools can be copied into the open DGN file. Once they are part of the open DGN file they can be modified and deleted. You cannot add, modify, cut, rename, delete, or rearrange tools in a DGN library without opening that DGN library. You cannot change the standard Application tools.