Wait! Don't throw away that tiny remnant of pencil. Germany has the answer, the Lead-pencil-lengthener Bleistiftverlängerer. I have seen period examples of these in original writing kits and finally found a modern made version. This is an extremely practical tool for your map case especially when you consider how hard it can be to get new pencils delivered to the front lines. It is quite simple to use just inset the pencil and move the small ring band up to pinch the steel sleeve down to grip the pencil. It measures a little over 11 cm long.
Weight with packaging: 0.1 kg (Make the most of DHL shipping, learn more here.)