I have realized that there are quite a bit of difference between the colors of different filament brands. Opacity, intensity, tone, and florescence are some of the properties i have found differ between brands.
There are two zones, one large where you can write down the name of the filament and a small area with 0.1 mm, 0.2 mm, and 0.3 mm thick areas so you can compare how thin sections will look. The hole is 4 mm.
[7 of Aug 17]
Added a couple of models with 0.4 / 0.8 / 1.2 mm as well as 0.5 / 1.0 / 1.5 mm to match the wall thickness of common nozzles. Print with och close to 100% infill to get a realistic opacity. Also changed the hole size to 5mm. Leaving the old one up if you already used it and want your new ones exactly the same.
Designed with OnShape: https://cad.onshape.com/documents/b94e9ec9aee632c4fb8631e7/w/708a8fcb904cff13521875fb/e/dcfb36abf0dee5eefba083d8
Make sure all your layers are 0.1 mm to make full use of the transparency window.