You know what they should invent? Paint markers. Or pencils. Some sort of stick-like instrument useful for distributing paint, anyways. Then all us klutzes who are crap with fiddly little brushes but reasonably okay with a pencil could paint things with fine details that we’re actually satisfied with.
I know they already make watercolour crayons. Someone just has to invent a system for acrylics and/or oils.
 Yes, I *am* staring at some paintings I did last year. Why do you ask?