DID NOT WORK!!!!!!!!!!!!!! Tons of money wasted.
My Hudini daughter got her thumb out no matter how I did it, and she managed to suck her thumb until she was 5. I went through the same thing as you are. At 2 we tried the polishes etc and she did the same thing. Then we tried the guard did not work.
What finally worked for us at 5, was we put the polish on and then we put socks on her hands (They have to be on tight or they take them off) If you put duck tape around the wrist so they can't slide off, but don't do it too tight that you cut off circulation. It is a fine balance there. The first 2 weeks were ROUGH!!!!! But it kicked her habit.
EDIT: For those that say don't stress about it, that irked me to no end when dealing with this. Each situation is different, but my daughter would suck her thumb so hard, she actually reshaped the roof of her mouth and if we didn't get her to stop she would have needed an implant to open her mouth again. It isn't just a thumb that doesn't cause problems. The problems are real that come with thumb sucking. We are still having issues with our daughters mouth and it wasn't just the dentist that was concerned, but her Dr. too.