In high school I was part of an engineering team, and to help raise money for new classroom equipment we designed and sold fidgets and small toys. As part of a friendly competition, we each created our own puzzle designs. Mine ended up winning “hardest to solve.” Since then, this puzzle has been sitting on my desk. Over the years, plenty of people have picked it up and tried to figure it out — some confident, some frustrated, and only a few successful. Now I’m sharing it here for others to try.