better than ball and cup provides a bit more challenge

http://www.folkartisans.com/images9/thhk_th3.jpg created from this

version 2 of this is prescaled down to fit on printer use base2 and ring2

looks like both pieces needs to be scaled to 0.8 also print the ring on the flat side

ring could be scaled down a bit more to make it more challenging but its really hard already

remember to wash it after printing to avoid hands from having the warm burning sensation PLA fumes make

i used a 2' peice of rope for this , no shorter than 20" or its very hard to see without being lucky

https://www.thingiverse.com/thing:3083526 for another harder version