This is a decorative display stand for Stabilo pens. They have a diameter (flat sides) of 7.8mm, check if yours have the same size before printing.
"sleeve.stl" is the base model, the other two have minor modifications for variety.
Printed pictures are "sleeve_bevels.stl".
Optimized for 0.4mm nozzles. Printed with 2 perimeters close to no infill should be needed. Check that wall are "gapfill"ed to save printing time.