There are some pens that I have seen pictures of, or references to, but I do not own and have not had the pleasure of opening to inspect.
Curzon’s “Top-Lever” pen
A small lever on the butt end of the barrel lifts up to results in compression of an internal pressure bar. Put the lever flat again to draw ink.
Hartline Blotter Pen
Does it use the same mechanism as the Wirt Simplicity? Or perhaps the Dr. Faber system? Or is it something else? Please let me know! Send pictures!
Houston – not the dropper and not the Snap-Fil
There is a Houston pen where the pointed/tapered end of the barrel screws off, and then screws into a hole on the side of the barrel. Then it is the knob, stud, or button used to compress the sac.
H.B Smith stud filler
I saw this pen for sale once on ebay. There was a sort of nob or nut on the side. It unscrews a bit, and then you push it like the stud on the Jaxon/Conklinette. At least I think that is what it does.
Whitney (Whitney Richards?) COLLAR MECHANISM
I once saw a Whitney pen with a metal collar. I think I read somewhere that sliding the collar moves an internal pivot like the Schnell/Bankers Master Special filler.
Under the blind cap is some sort of a ball. Is this just the same toggle as the Eagle toggle filler, or something else? I saw a picture – not sure what it is.
Cameron Macniven bulb filler
This one is admittedly not interesting. It is a bulb filler with metal bars on either side of the bulb, I suppose to make the bulb squeezing a more elegant experience.
Nettuno – twist barrel sections?
I believe I once saw a picture of a BHR pen with a zig zag joint that is twisted to fill.