You can specify custom blocks and profiles to add to or replace individual railing components. You can add to or replace posts, dynamic posts, and balusters can be added to or replaced, and you can add to (but not replace) other railing components.
When you add a custom block and profile, you can specify several rules for positioning and scaling the new component. Each custom block or profile is also added to the display properties so that you can control its layer, color, and linetype. Be sure that the objects used to create the custom blocks are created with their properties designated as ByBlock. Otherwise, they cannot be controlled through the display properties.
After you create custom blocks and profiles, you can attach them to railing styles. Using custom blocks and profiles, railing styles can provide a much richer and more flexible set of railing graphics.