I've been trying to discover whether anyone ever produced a clutch-type lead holder (not a propelling/automatic pencil) in 0.7 or 0.9 mm, and have had no success. Has anyone ever seen such a thing?
I have no knowledge of anything like that. I think 0.7 or 0.9 mm leads are just to thin and frail, therefore impractical, to use with drop type clutch mechanisms. It doesn't mean they don't exist or that someone hasn't, at least, tried to build them.
I also think I never saw an Eagle Turquoise "Twelve" lead holder before. Now I want one, it's a beauty!
I've wondered about this exact same thing on multiple occasions. Why should 2mm be the smallest lead available in a clutch pencil? It seems like 0.9mm lead is pretty robust, I bet it could handle being used in a clutch drop type pencil.
If Staedtler, for instance, made a Technico Mars lead holder in 0.9mm, I would totally buy one or two.
Are there any 0.9mm mechanical pencils out there that could be adapted to behave like a lead holder?
I just took the tip off of my pentel P209 and it already behaves like a lead holder except that the mechanism isn't secured to the plastic body without the tip. If you could find a nut or something that matched the threads, you could have a 0.9mm lead holder simply by replacing the pencil tip with such a nut.
Alternatively, if you had a clean way to cut through the metal tip, you could cut the bottom off and leave that threaded to secure the insides to the plastic body but still have the clutch exposed.
With Pentel pencils, you can simply remove the tiny little o-ring (sort of) down inside the metal tip. Not quite what I'm after, though. I *think* I could modify one of the old 0.9 mm Parker Cartridge Pencil cartridges to behave like a clutch pencil: the clutch/collet is already in place and I would just need to remove the internal bits that move and hold the lead when the clutch is open. I'd hate to do that to something irreplaceable, though.