Thinking on this further...symbols come about through intense practice over time, through religious feelings and meditations, and religious application/practices of thoughts and ideas.
You can read about the development of "Om" on Wikipedia to see that it is a long and complex process born out of the usefulness of the symbol.
So creation of an Epicurean symbol must have an interface between feeling and usefulness.
Right now I see a usefulness of the 20th moon symbol that Eikadistes created, as this is something all Epicureans would partake in.