doesn't that defeat the whole point though? because then i would have to manually adjust it physically. The while point is that this will be in a completely enclosed housing in which i can't access it later to fix things. unless I'm reading it wrong I'm not sure where you're going with the button and the potentiometer
i gave you basics.. for manually, and i did say "auto" would be in coding.... but when building something.. you should always give yourself a backdoor option incase ever needed.. AGAIN, you never said what it was yer building or how you intended on controlling the leds.. as AARG reminded you..
so.. you have to be more specific.. so how can anyone help you without specifics? what will it be used for (purpose)? the more detailed you are the better help you will get. we can't help you if we don't know what it is yer trying to accomplish.. controlling leds is more in detail depending on the project.
you can make an led game on 100 leds and you can build a 100 led audio visual organ.. each are controlled differently.. see what i mean? what is it that yer trying to make? telling us you want to control 12 single color leds seperately isn't enough info for us to go on.. just saying