Prayer wheels, as used in Tibet, are essentially machines which 'chant' mantras for you when you have other things to do, helping you toward enlightenment and positive karma even when used in a distracted manner. Fidget spinner are a largely pointless fetish used supposedly used to release 'nervous energy'.
By combining the the purpose of the former with the design of the latter, by way of engraving mantras into spinning section, Buddhists can accumulate wisdom and merit (good karma) while in the office, on a train or even watching television, or even 'double up' using a spinner in each hand. It should, of course, be marked to encourage clockwise use in the traditional manner so as not to accidentally undo earlier karma, or be fitted with a braking system if used 'widdershins'.-- TheBamforth, Dec 11 2019 How does the wheel know who it is chanting mantras for?
Can it be done vicariously?-- pocmloc, Dec 11 2019 While not having a detailed knowledge of Buddist theory (but not theology, since Buddhism does not recognized any deity or deities) our understanding is that spinning a prayer wheel by, for example, unattended wind power increases the net "good karma" in the world (Universe), which trickles down to every living thing in its current incarnation cycle.-- 8th of 7, Dec 12 2019 random, halfbakery