I've long admired the Rider "Perfection" pen, produced by the J. G. Rider Pen Company of Rockford, Illinois.
Based on U.S. Patent Nº 737,920, awarded to Jay G. Rider on September 22, 1903, the pen was an eyedropper filler without a separate section. Instead, it had a special feed that was notched on the bottom so that you could use your fingernail or the pen's clip to pull the feed out, leaving the nib in place, to fill the pen. Here's the relevant patent drawing.
Well, my admiration is a little dimmed these days, I have to say. While I was doing some research this week on the Laughlin Manufacturing Company, I discovered a patent taken out by Joseph F. Betzler and assigned by him to James W. Laughlin. U.S. Patent Nº 686,902, dated November 19, 1901, is in essence identical to Rider's later patent.
Laughlin never made pens to Betzler's patent, and now I wonder whether Rider might have seen it at some point, varying his design just enough that it would pass muster at the patent office.