I would recommend Loops by Yigal Mesika. I assume you know that there is no such thing as invisible, so you'll need to be in specific light conditions, but I don't think you'll find a less visible thread that doesn't break after 1 or 2 uses. Mine last for about 4-5 performances of Haunted Deck(that's what I mostly use them for), which is pretty good. If you just want to levitate cards or dollar bills, it'll last days.
Answered at 06:02pm on November 17th, 2013 by Amadakon (0 karma)