You can find any tool by the Menu Structure HERE: https://turbocaddoc.atlassian.net/wiki/display/TC21UG/Menu+Structure

You can find the menu location of any tool by name HERE: https://turbocaddoc.atlassian.net/wiki/display/TC21UG/Tools+Mapped+to+Menus

Double Line- Polygon

 
Creates a regular (equal-length sides) double-line polygon. For the interaction, see Polygon.