I think that you should print the part of 0.6mm(Part with a letter and the hexagonal design) by setting of the slow speed from the bottom.
I changed a color at 0.6mm from the bottom and printed it. (from White to Black)
Filament: PETG
Support: None
Infill: 20%
0.20mm
The author remixed this model.
I added a hexagonal three-dimensional design to an original LCD cover.