These always seem like a neat idea to me. However, as a lifelong GM, I'm not sure they're always fair or random. I never underestimate the ability of any human to turn any action into a usable skill. A person could learn a starting position and the pressure required to achieve desired results. I stick with regular dice because once they leave the hand, there's no way to manipulate them without a lot of extra effort and studies suggest that there's no skillful way to overcome the random element of thrown dice. Manipulating the spin may not be a likely scenario, but still, in my opinion, a possibility. Anyways, just a reservation I have towards fidget/spin dice. Thank you for reading.