I was recommended this video on Youtube (Test You IQ with this puzzle): https://www.youtube.com/shorts/xfhooLun4X8 So I created it myself for printing on my 3D printer ;-) The goal is to free the ring without any force!

Some points that I found critical, when I created this puzzle: You'll need a rope around 45cm length with 3mm in diameter, and some glue. Depending on the print parameters it may be necessary to enlarge the small holes a little bit, so You can slide in the rope. The solution seems to be very simple, but this way will only be possible, if the loop in the rope is too large and could slide over the octagon ;-)