I tested out something, so for the benefit of the readers: don't put something flexible such as a plastic sprue piece in the Dremel. Anything flexible spinning that fast can turn into a weed eater. I knew what I was doing with that experiment & took precautions when I tried that out, so no harm was done.
I do have a Dremel that I sometimes use as a paint mixer though. I stick one of those fat & long toothpicks in it with the flat end down / pointed end in the Dremel chuck. That's also dangerous, but I'd rather a piece of wood with its likelyhood of just breaking off and falling instead of turning into a weed eater or slinging chunks of glass jar rims from some sort of metal stick hitting it. I do that with a multi-speed Dremel at its lowest setting. It says in the manual that this first notch is in the range of 5,000 to 8,000 rpm.