Trapped Ring (Wit's End) Puzzle

The goal of this puzzle is to remove the large ring, printed in red in the images. Assemble the puzzle as shown in the first picture when you make it. The string is only required to be around 10cm long, but a length closer to 20cm makes solving the puzzle less finicky.

I first came across this puzzle on display with several others in a souvenir shop. After spending a fair amount of time messing with all the puzzles they had, this was the only one I couldn't solve, and so I decided I would buy it to be able to work on it on my own time. However, it wasn't on the shelf where all the other puzzles for sale were sitting, and when I asked the shop owner she said that the man who used to make them had passed away a few months ago. This meant that they couldn't get any more units in to sell, and the one on display was the last one they had.
So, having just assembled my first 3d printer a few weeks before, I decided to take some pictures and attempt to recreate it. After spending some qua