There are quite a number of origami butterflies that have been designed. But there are relatively few origami butterfly bookmarks. And of those few, I think the most beautiful is Grzegorz Bubniak's bookmark.
I have stagnated in my folding these days, haven't really tried new things. So this bookmark made an interesting change. I found the steps to be more complex than what I have attempted so far. But despite that, the instructions were clear enough that I could follow and complete them.
The difficulty level for the bookmark is intermediate, I would say. Moving from step 4 to 5 presented the first challenge for me. Going from Step 9 to 10 was also interesting. I had to closely follow the valley and mountain folds to complete the step. I also needed to figure out how to make a swivel fold.
Model Details:
Model: Butterfly Bookmark
Creator: Grzegorz Bubniak
Website: GregOrigami
Difficulty Level: High Intermediate
Paper Ratio: Square
Paper Size: 5 inches
Tutorial: Youtube
Diagram: Dev.Origami