Build me an electronic cigarette

We would like to build an electronic cigarette which works with the same principle as the 4 colors pen (photo joined). The product would have 4 tastes in the same electronic cigarette and people would choose what they smoke with the 4 different buttons. We would make or own tastes so the product would have 4 compartments.
People must be able to replace their tastes.
For the rest you are free to choose.