Print with 0.4 mm nozzle, 100% infill, first layer height 0.16 mm and the rest of the layers 0.08 mm. Start with black and at layer 11 change to white. You can use any 2 contrasting colors. 

Please note, I use my own recycled filament from PET bottles, so my prints are not so clean, but the result varies from type of filament to transparency of the filament.

To download the file click the green button ´´download STL/CAD files´´ under the print profile, there you will find STL. I will add the print profile later. You will find all the settings in this description.