This is my take on the classic Oliver String Puzzle. The one shown was built from scrap wood, a ring from a previous project, purchased wood beads and rope.
Build Instructions: https://www.instructables.com/id/Oliver-String-Puzzle/ I've included STL files for those that would like to print it. If neither of those work for you, you can buy a similar version from Amazon: https://www.amazon.com/gp/product/B005IDO5UK/ref=as_li_tl?ie=UTF8&tag=jingle1000-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B005IDO5UK&linkId=e2a10c989082c323b48908823256c848

The goal is to remove the ring from the puzzle. My kids and wife found it quite challenging. I would rate the skill level at 3 out 5. If you can't figure it out from the pictures, refer to the video.