For fine edits slates sharpened pencils designers and architects typically use fine-grained sandpaper. But it may not be in the right moment at hand. Then I do the just use for this purpose a matchbox: always available, convenient, and the result is not worse. Gravityzoo-impromptu to make you less than a minute, even to glue nothing. The bottom wall of the lid box is cut, bend the top half and walls with arch beef up. The resulting “accordion” put in a match box-boxes (in the figure it is clearly shown) — it is well kept there as a spacer. I think additional explanation is not required.
E. SAWICKI, Korosten, Zhytomyr region.