I like them and use them a lot, I spent years doing readings on almost every possible thing to get a feel for them, because i wanted the coinvenience of being able to work with something so simple.
I posted the stuff I’ve found out so far about pendulum use here - one bit I left out is that you can get very effective answers by asking about your relationship to the action.
For example, you want to know whether to ask someone on a date, or whether to buy something expesive, asking “Should I do this?” leaves too many variables about what “should” could mean, plus all your subconscious baggage can set in, so I found that asking “If I do this, will I regret it?” gets a clearer (and, so far, accurate) answer.
As with a lot of stuff, for some reason it’s best to frame it in the affirmative i.e., “Will I regret it if I do …” not “Will I regret it if I don’t do …”
I’ve found this was generally a better question than “Will I be happy with the results of …” - maybe, just like people have premonitions over deaths etc, but not over finding $20 in the street, our minds are more likely to warn us of potential loss and danger - psychologically speaking, studies show we’re usually risk-averse in most of our financial choices, for example.