Here is a very simple, easy and quick test that I use to check what thickness I need to make my models to get the desired transparency/opaqueness or colour blend from layering different colours.

The model is designed to be printed with 0.16 layer height. Have your base colour in the first two layers, and then make a filament change at layer 3. but you are welcome to use it as you see fit,

First layer height - 0.2
Layer height - 0.16
Change the Filament Colour at layer 3.