Lead in: I always favored the old SFB C9 over the C8, and was a bit bummed that it lost its place in the SFU by C8 refits and the launch of the C10. So yes, I did my own FC-era C9 card.
Question: Would verbally describing the card here or elsewhere be the same as "posting?"
My understanding is you can talk about game topics to your heart's content, with a very few exceptions (no indicating where pirated ADB content is hosted, etc.).
There is no problem describing differences between ships, or differences between ship cards. In fact, I have done it multiple times myself. (Including, I believe, on how to make a C8 into a C9.)
Just to let you guys know, there are hardly any custom built ships in my collection. Just copies of SFB/SFB designs. Just wondered if it was ok to build your own copies of SFB designs for personal use. Mostly just copies of communique ships basically.