Metal glue bottle tips are hard to find if you do not quite creative.
I have found them at Michaels in the stained glass/glass painting section.
Plan B is the make-it-yourself plan. The plastic screw-on applicator part for the glue bottle is easy to find at Michaels/JoAnns/etc. and the metal tip is nothing more than the metal tip of a mechanical pencil. The metal mechanical pencil tip will screw right on to the plastic applicator. Viola - a fine tip for a bottle of glue.