Hand painted tree rings - would recommend putting all tree rings on a board (which could be painted a coordinating color to add pop to the art piece. Really neat idea for after school kids. Might just do 9 rings in a square frame!
Ingenious Breathtaking Wall Art Decor Meant to Feed Your Imagination
12 Modern Tree Circles Amazing Colors Abstract Paintings on Wood by HeatherMontgomeryArt Using wood and using wood ring to bring out the natural beauty of the wood ring give more stableness in the art
Make Them Wonder: Inspiration Pieces paint on small sawed tree trunks and then paint rings on the rigs.
Eco Friendly Reclaimed Wooden Coasters - set of 6 coasters - by Earth By Wendy
37 Thoughts Blowingly Stunning Diy Wall Artwork Projects That Will Mesmerise Your Guests
Set of 15 Large Wall Sculpture Colorful Modern Abstract Danish Modern Wall Art Tracy Melton