i really like the idea, double shot keycaps should last forever, the 2 things to consider are, 1 using the correct material to let the light pass, some materials will degrade the quality of the color or change it a bit in an rgb keyboard since the light is not as strong as in a single color keyboard, and 2 using the correct font as not all the fonts can be done in double shot, the placement of little inserts for the letters like B, O, P, etc from a munufacture point of view will be imposible, a nightmare, or it will need to happen in 3 stages, 1 the outside of the key, 2 the letter itself, 3 the insert for the loops, and doing 3 stages with that much presicion is really really difficult