My four-year-old is still sucking her thumb, but is starting to think about quitting. When I asked her how I could help her to remember not to suck her thumb, she suggested that I make her a glove. So, I did, but just for the thumb. I can’t guarantee that this will work for everyone, but there are two things about this approach that make me optimistic:

1. It was her idea, so she is invested in the project, which is great, because if she doesn’t want to stop, she won’t.
2. It works; at least as long as she is wearing it.

This is a pattern for a thumb-cover, which is used to remind a child not to suck on his or her thumb. Any fingering weight yarn can be used, though you might prefer it to be machine-washable.