So, after much longer than I expected, a lot of hard work and a lot of stabbing myself in the fingers, she's done!
Rarity is approximately 14" tall, 16" including her horn, and approximately 9.5" inches from nose to flank, not including her tail. Her head is jointed and can be turned a full 360 degrees, and she is almost completely machine sewn, though her mane, tail and horn are hand sewn on.
She is made of minky with hand embroidered eyes and cutie marks. Unfortunately there is wire in her mane and tail, I was hoping to find a way to do it without wire but have thus far been unsuccessful.
More views of Rarity here
To head off questions about this; I do want to start taking commissions, however I have no clue what to charge so anyone interested will just have to be patient while I work that out.