I have become completely enthralled with the sleeve worn but the member of the Technic League on pg 33 of Numeria.  This is obviously how the TL recruits new members.  With great sleeves.

The sleeve part looks like a standard 2-piece jacket sleeve down to the elbow.  The bodice part has an undersized side panel, which ends just a few inches below the armscye (The seam where the sleeve is sewn to the bodice).  I have no idea what to call this, so I’m going to go with “gusset”, even thought that’s not what it is)

The coat is made from 2 different fabrics, one for most of the coat and one for the under sleeve and gusset. Presumably, this is for ventilation or freedom of movement.

I can’t wait to reverse engineer it and see how it works.  There’s also some interesting chevroning around the waist.  I have nowhere to wear this coat, but I’m dying to figure out how it’s made.