Like many of you suggested, I decided to go with the short cape with sleeves. But, since this little book is new to me and I still wasn't entirely sure about the look, I decided to make a muslin first.
First of all, the instructions in the book are decidedly sketchy. Of course, I don't have the slopers it used to come with, but still...
It doesn't mention how deep the cut between sleeve and body should be, or at what angle to the straight grain or what distance to the original under-arm point it should be made. Either of which would have been very helpful to get the right placement. It only tells you that the sleeve hem is 21 cm wide on each pattern piece... And it does mention shoulder/sleeve length but not the length of the body of the cape.
If my theory is correct and this method of pattern buying/making never really took off, they didn't just have affordable patterns from the likes of Marion to blame for it...
Also, the text about what looks, at first glance like sleeves is not entirely clear either. They mention a slit between body and sleeve but don't really go on about the sleeves themselves.
And on closer inspection of the pictures, I noticed this:
Edges at those 'sleeve-slits'. Do they mean they're not sewn together? Or only at the very tip? That sort of defeats the purpose of including something sleeve-like, doesn't it?
I did stitch the slits on my muslin as sleeves. On one side, I also added a sort of underarm gore: a strip of fabric 5 cm wide between the front and back of the cape. At the other side, I just sewed front and back together.
Even when posing like the lady in the drawing, I fortunately don't look like I don't have shoulders at all.
The fabric I used for the muslin is a bit stiff, so I expect the cape to drape more gently when made up in an actual fashion fabric.
Oh, and the fabric tends to stick to the fabric of my jumpsuit, which makes the 'normal view particularly un-appealing.
In these pictures from the side, you can more or less see what I'm talking about with that underarm gore. Basically, it allows that half-sleeve thing to function like a real sleeve.
I'm still not sure about this thing though. It is more like a little jacket than like a cape and I don't know about its dimensions. It might be better if I made it a little longer...