For a better feel, it is recommended to place the eggshells more densely so that a three-dimensional effect arises through overlaps and the partial transparency does not seem 'undecided'. Instead of a continuously semi-transparent body, a clearly delimited ink-view window (densely above, running out towards the viewing window, or a separate small window) is visually more coherent. A screw cap on the filling grip requires a diameter-reduction step on the thread part, which is structurally a disadvantage. Hints on processing eggshell surfaces are also offered by Horst from maxpens.de, who has extensive experience with this technique.