Here is a list of Acrylic Colors that the Manu offers.
To get an Idea on how these materials might look on a keyboard, you could look at ShrimpKeys’ Acrylic Keyboards such as the V40105.
Colored A: 5x4
Colored B: 7x6
Opaque A 3x4
Opaque B 3x4
Special A 2x4
Special B: “Electric Blue”
ShrimpKeys Proto in Electric Blue pictures by gvb.