I keep a whole section of art materials just for the rowdies to use when they come to visit. Kids do love to paint and draw, but almost all of my grandkids have experienced "artist's block."
They are all set to paint and they ask me what they should paint. I suggest things like bunny rabbits, kitty cats or merry-go-rounds. Their reaction is "I can't paint that", or "I don't know how...you do it for me."
To encourage them to explore with their art I tell them I would like to see how they paint a bunny rabbit, maybe by watching them I can learn something about bunny rabbit painting...things I would never have done...like pink and purple polka dots and squiggles for a tail.
So, instead of me sitting down drawing a bunny and them copying me we sit down and let the grandchild draw and I do my best fo copy theirs. It is a good experience for both of us. Funny thing...I almost always like their bunny best!!!