To introduce kids to the idea of steam as a means of doing work and as a
tribute to Heron of Alexandria, I built this spinner engine from a
toilet tank float.  The top with the two jets unscrews so the float can
be partially filled with water.  Then a propane torch applied to the
bottom of the float gets the thing spinning nicely on its fishing tackle
"bearing".

If you build one, be sure to solder the float seam - DAMHIKT.  Also
think about adding a bearing at the bottom of the float lest it wobble
excessively while operating.