Here is my symbol for the Cardassian Republic
(19th century-Early 24th century?), which existed before the military took over (the Cardassian in the 4 lights episode stated that his childhood was under a Cardassia which was starving before the military took over, hence the rise of the Cardassian dictatorial state had to have come after that childhood, which would have been, given lifespans, probably around the early 24th century). It is based on a decal on a Cardassian building.
Like many things, this is for my TOS RPG to help flesh out the universe. I have a encyclopedic area for the TOS universe of the time and how everything is at the time. The Cardassians of these time don't really mean much. They're a small nation, with limited resources, who are like the Federation in a belief in culture and art and improvement and so on, but have none of the resources the UFP does. So they don't appear like they'll ever matter.