I made this jellyfish costume for my wife during on our Halloween build day here at Instructables. It turned out to be a great lesson on the value Instructables brings to the Internet. The costume idea came from a few costume sleuthing searches, probably some Pinterest results, and then onto an unnamed large corporate site with a pretty picture. I tried to follow what looked like reasonable instructions, only to find out that whomever was writing these instructions had never actually made the costume.
So here are my instructions after actually making this costume! It should take you a few hours to complete.