Remix of saipanda8801's nice pen holder (https://www.printables.com/social/269874-saipanda8801).
This one has 2mm (minimum) wall thickness for added stability. Otherwise the same.
/edit: I just noticed saipanda8801 has actually made a remix of his own creation with thicker walls as well, the original is removed and the new is very similar to this one except that saipanda8801 has rounded the shelf/wall connections on the new design.
The author remixed this model.