It is completely understood that you do not want to waste your paint if you have to repeat the painting the next day.  Well, it is possible. Yes, and it is simple too. For this, you have to wrap your roller in an aluminum sheet and then, you have to wrap it up in a plastic bag. Once done with the covering, put the roll in a cool and dry place like a refrigerator. But, you need to know that it will cause a lot of smell. So, your food items can be destroyed.  This is its major drawback.