I made a magic ball, the hardest origami item I have attempted or made...
It took me three times to finally get a ball. Third time's the charm. It took me half an hour to realize my first attempt wouldn't work because the paper ratio was incorrect and my folding was going slow.
The second attempt went better. I found a faster way to fold all the Xs and my ratio was correct. However, I learned my paper was too small. The third attempt went much better and only took 5 hours to create.
I made it out of a calendar from Japan Air. In total it took me over 6 hours to finally create a magic ball after debating for months on whether I should fold one. I was really really excited when I finally completed the model! :)