Why am I thinking about capes ALREADY? The weather has turned chilly again in London, ahem, so I am thinking about capes. Perhaps keep this lightly simmering until winter if you are in a place that is warmer. The following images show that it would be easy to deconstruct a jacket to make a fitted cape. You could either simply cut holes in the underneath of the sleeves and put yours arms through, like the image of Hannelli below. Or to make a jacket like the second and third images, you could take an oversized coat that is too big in the shoulders, cut off the arms at the shoulders and sew the arm holes shut (aiming to create a rounded shoulder). Finally, make cuts in the front of the jacket to create the cape arm holes.
Image: Altamira, Hannelli Mustapata