http://terraria.gamepedia.com/Terrarian ~ Wiki page

Tips The size makes it a bit difficult. Try to be as neat as possible when making the axis. For string I glued a piece of 25 cm string onto the axis. Do the knot how ever you can adjust the size. (Mine isn't a yo-yo knot but it works for this papercraft.) If you don't have string a thin strip of paper will work. It wont affect the performance of the yo-yo. (Because it doesn't function at all.) :)