Spares in earlier days: worn Schwan lost in Bristol,
Y&C I just lost, and no-name (maybe Niji) that remains
||I'm not much for body ornament, but for the past 30 years one thing I've had on me when dressed is a mechanical pencil. Something to write on can be found nearly anywhere, but something to write with cannot.
Back in University I came across The Best Mechanical Pencil Ever: a Schwan Stabilo Microtom 3110. It's a very unique pencil, having a retracting tip, which saves on belly-poking and shirt-pocket holes. It's been more than a pencil in my life - the point and cap have been very handy tools over the decades.
Over the years I bought them whenever and wherever I could find them. They were discontinued by Schwan and continued on by a couple other companies under the Selectum (in black, and slightly different) and Yasutomo Y&C Grip500 names. Retracting mechanical pencils are not fashionable and I've since found no modern replacement.
[2015.03.27 Edit:] There are a number of "retractable" pencils available, but I've had to change the word I use for these pencils to retracting because their unique feature was that they were spring-loaded. Pushing the cap extended the shaft from the body as usual but there was a stopper mechanism that loaded a spring. Pressing the pocket-clip released the stopper and the spring pulled the shaft into the body. Very clever. Too clever for most naive users though - not knowing the clip was a trigger meant a surprise disappearance of the business end of the thing mid-writing, something I saw in two decades of being the only guy with something to write with and offering mine with a proviso.
Plus, these pencils lent a stylish flair to using something pretty nerdly. Pencil comes out of pocket, pressing the cap down until the click of the stopper, maybe an extra push to advance a bit more lead and ready to write. Rectractables can do that. But with these pencils a press on the clip and back into the pocket in one motion. Very tidy. Retractables need to have their shafts pushed into the body manually. Less tidy.
Sadly, I lost my last working pencil the other day, and all I have left is a broken one I kept for parts. I have 3 Selectums, all missing caps, probably because they tended to fall off, and only a few parts seem interchangeable. I also have a few Staedtler Retro retractables but Meh.
I've Googled at various times and found very little. So perhaps the Internet, which I know passes by here occasionally, will be of serendipitous assistance.