Here's a fun fan project by Hyrum Cooper. It's a Chain Puzzle Simulator that runs in your web browser so you can play around with a virtual version of the puzzle. I think it's super neat, especially the solving algorithm that iterates to find more efficient solutions and then walks you through it step-by-step. Great for the real puzzle nerds seeking systematic solutions :D

Here's the simulator : https://bit.ly/the_chain
More from Hyrum : https://github.com/hyrumcoop
3D Printed Chain Puzzle : https://bit.ly/chain3D
STL Files : https://bit.ly/theChain