If you don’t have the DIY inclinations to justify purchasing a real Dremel, this 3.7V cordless rotary tool from Tacklife is a low-power alternative for $16 with promo code 7UVGHSV2.
You’re probably not going to use this to cut through rebar or anything, but it’d be perfect for quickly sanding the edges of wood, polishing jewelry, or even carving Jack-O-Lanterns. It even includes a bunch of dips for various jobs, and yes, it charges over USB.