[hermitcrab]

I'm not sure that corn starch would stay as a fine powder long enough for that to work.

However, if you have a long cardboard tube:

* place the tube vertically with an ignition source at the bottom (small candle perhaps)

* pour fine powder in the top (may need a step ladder if the tube is tall enough)

* satisfying whoosh

Don't look down the tube as you are doing it and don't do it indoors, obvs!