Thanks for the kind words about Stardraw AV - we're glad you like it.Probably the best way to create new rack/pictorial symbols is to use the contents of the Generic Components library. Start with a Rackmount Unit and go from there. The Generic Components library for Rack Layouts contains rack mount cases, handles, knobs, buttons, switches and faders to name but a few categories of component, and even manufacturer logos.
When you've completed your symbol, simply drag it into the Library List under the My Libraries root. You'll find it helpful to build a folder structure similar to the Offline Libraries structure, i.e. 'Racks' | [manufacturer] | [group]. Rightclick to create/rename/delete folders.
I hope this is helpful.