FuÇando na internet achei isto aqui.
O cara usa Future e corante para comida. Vou tentar Future com tinta acrilica.
The 90mm armor vision glass blocks (M2 to M5) with all of the support sprues connecting them together removed.
I dipped the armor vision glass blocks into a mixture of Future and green food coloring. I used several drops of the food coloring to achieve the color that I was looking for but you could apply as much as you want to suite your preference. If you don't already know about Future here is a link that will give you all you need to know about this product.
The armor vision glass blocks after dipping them in the Future and green food mixture. As the Future sets up over several days the color will fade away leaving just a hint of the green color. Note the high crystal clear shine after dipping the parts into the Future.