Zippo is the figit toy of boomers.
Roller bearings, they're so satisfying.
Arch lighters. I have one that fits in a zippo case!
Bumble ball, it's a baby toy with a spinning motor in it, bounces around wildly when you hit the button. As an adult, these things are hilarious and a holding one is a great ADHD stim.
You can make a herbarium out of snack jars from dollar tree. I've never had so much fun looking at a jar of dirt.
Oragami. Any time I'm left unattended with scrap paper I the area with butterflies and flowers. Keeps the hands busy and everyone gets blown away by it.
Other guy got me right, terrarium is what I was thinking of lol.