First person to get this button filler identification correct (or remotely close) will win a bottle of vintage Penit Royal Blue ink shipped to their CONUS address.
Pics:
With the ink you will get
Capped unit
It's a little longer than a streamline Parker Duofold Jr
Looks like a Ripet. Kind of like a Ripet Popular, but still several distinct differences. However, the button design does look very similar to Ripet, so maybe it is just a different model?
Lots of great answers showing me that members are really doing their homework!
First clue: Delta, Kosca, Penol, Benco, Ripet are all from the correct continent.