This has been done before and with different approach, but this is what I had in mind. I'm going to make a fidget spinner into a brushless motor. Sort of.
I'll attach magnets to the arms of the spinner (the grey rectangles). Underneath the spinner I place an electromagnet, which will be driven by a motor board (handy H bridge with protecting diodes). I probably need to take care of restricting the current.
I might place a hall sensor or two somewhere to make it act like a real brushless motor. Reed switches would do the job without a motor board and a microcontroller. But having everything controlled by an Arduino gives me the possibility to try different things here. What timing parameters do I need to make the spinner start without me helping it to start. And without hall sensors and reed switches, how does the spinner react to tempo changes. I expect chaotic behaviour at some tempo and very regular spinning at other tempos.