I assume you want to model the buttons, print the buttons, use the printed buttons as pattern to make a rubber mold, then use the rubber mold to make final part using epoxy?
I’m sure you are aware that 3D printed parts have layer marking and other surface defects on them, meaning when you make rubber mold based on 3D printed object, the mold itself will have such defects. I have done this in the past - 3D print, surface treatment with acetone vapour, still having surface defects. Best is to find a CNC machinist (3DHubs starting to do CNC, look around) to make the pattern, then you can use it to make rubber mold and your end product will have much better appearance.