1920x1080 version here [link]
Okay, I got some sleep. Time to write then.
You know what? I think I know why I haven't drawn Octavia before. It's this goddamn... cello... double bass... whatever. I don't even know what is it! Bass has a slightly different shape, but cello has longer spike. Can't tell anything about the size because ponies.
Anyways, it was pretty difficult to draw.
UPDATE: Okay, you say it's cello and I believe you.
But apart from this cello Octavia is a pleasure to draw. Long, curvy lines, toned colors, elegant clothing... Speaking of clothing - why doesn't she wear a dress? Well, I always magine her as a very elegant pony, but more into men's fashion - suits and so. It just fits her so well!
Other Steampunk Ponies:
The Inventor - Twilight Sparkle [link]
The Timid - Fluttershy [link]
The Lady - Rarity [link]
The Mechanic - Applejack [link]
The Pilot - Rainbow Dash [link]
The Random - Pinkie Pie [link]
The Princesses - Celestia and Nightmare Moon [link]
The Dentist - Colgate [link]
The Flyers - Spitfire and Soarin' [link]
The Smuggler - Carrot Top [link]
The Messenger - Derpy Hooves [link]
The Dreamer - Lyra [link]
The Professor - Cheerilee [link]
The Evil Queen - Chrysalis [link]
The DJ - Vinyl Scratch [link]
The Soldier - Big Macintosh [link]
The Illusionist - Trixie [link]