thank you all guys for your feedback.
And indeed, base color of the plastic plate is white and the edges can easily be colored with a black marker. I noticed it later and should had mentioned it. The holes are cutted out after printing, so it is not possible to color the inner edges automatically. And when I use a black base plate, the plates will not be translucent.
Be careful with the marker. If the ink comes on the front surface, you can see it. Stay within the lines.