To make a throwable clone potion is pretty simple, you just use /execute @e [type=snowball] ~~~ execute @p [x=~,y=~,z=~,r=2] ~~-1~ clone (coordinates of item you want to clone) ^^^ masked
But I cannot for the life of me figure out how to make a potion like this that only replaces certain blocks. Say you have a massive building made of stone brick but you think it would look better with polished blackstone brick but dont want to replace every single block by hand. Having a potion to throw and replace only the stone brick would save hours. Any help would be greatly appreciated. The wife is a mega builder and im desperate to help her, thank you.