paper towel will catch any drips. if the paint has a lot of loose debris, you may want to put a paint filter inside the funnel. once the paint is in the bottle, remove the funnel and drop about six marbles into the paint.
when it's time for a touch-up next year, you can shake up the bottle (and let those marbles do the work of mixing up the leftovers) and go. this technique will also save space in the garage. 