A self-washing brush with a paint-injection system coupled to a digital paints mixer? Add a system to only harden the paint when a special wavelength UV light

A self-washing brush with a paint-injection system coupled to a digital paints mixer? Add a system to only harden the paint when a special wavelength UV light is shined on it (maybe include the "hardening lamp" in brush's head?). Add away to switch between jet-mode (spray can paint) and brush mode, and you get a graffitty artist's wet dream. Joke aside, with paint and anything physical you got constraints of physics and chemistry. And anything too sophisticated will be expensive and prone to breaking so nobody will use it. Try to make it reliable and it will have the cost of a piece from an F-35. None of these constraints exist for software, so you don't really have any excuse to not do UX/I right.