Sarmatian Clothing on Kosika Vessels

[Holly Herda]

Okay, so I was initially going for the same type of kaftan as Sutoris on the "Show Your Sarmatian Warrior Impression" thread, but I've become intrigued by this guy's jacket from the Kosika vessels.

So my question is, can anyone help me work out a pattern? Sadly I have very minimal sewing experience. (I showed it to my dad, who's my helper, and it's a bit beyond him as well.)