I haven't designed a new garment in a long time... not since leaving school I think. I only developed and refined the designs I've already got. This however, will probably be the first new design of mine for a while.
It's a modular jacket, so the base garment is a short vest. Then you can attach sleeves, a collar, and a skirt, or short sleeves, or puffy sleeves or a tail or pockets etc. etc. etc. Right now I'm just working on the fit of the torso, and hopefully I may have time to finish it before this next winter is over so I can actually wear it.
I'm planning on having it properly tailored to fit. The first sleeves will be constructed with a bend in the elbow and will taper to the wrist so I will need the front half of the arm to open up. The skirt I want to make for it will be double breasted to match the top half and will function the same. It will also have pleats on the sides and back.
I think I'll probably wax it as well, to handle the wet winters of the NW.