Tower Ring Puzzle

At the risk of sounding like a recipe blog… When I was young, my Grandpa loved to show me physical puzzles to solve. The solutions were never immediately apparent, and seeing it in action always looked like magic. Grandpa has long since passed away, but I have fond memories of him and his tricky puzzles.This was one such puzzle that survived the years. The objective is to remove the ring from the central tower from under the string. Originally, there was a second string/set of washers/white plastic obstacle rings crossing the other way, but as a six-year-old I couldn't figure it out. Grandpa felt like I could handle one string, and so he cut the second off and threw it away. I've never forgotten how it looked before Grandpa modified it, and now that I have a 3D Printer, I'm going to try this again. There are two versions to assemble (and print profiles to match): Easy mode (one string) and Hard mode (two strings). The objectives for both are the same: remove the central rin