Coathanger ‘chimes’.
Bend a metal coathanger until it is rather straight. It will be something like 1 m long.
Tie light sewing thread to the coathanger at the 1/4 to 1/3 points (somewhere in there).

For a class demo, attach the free end of each thread to the botttom of an empty container (oatmeal, raisins, or an empty can of something). Or hold one end and attach a container to the
other end.

When the coathanger is lightly struck, a very pleasing ‘chimes’ sound will be heard from each container, which acts as an amplifier.

For a solo version, place the free end of each thread over an index finger, and place each index finger in one ear. Now the chimes sound quite rich, much better than with a container for amplification. (Not recommended for more than one person, for sanitary reasons.)

Theory. For a long circular rod free at both ends, the resonant frequencies are

    w = 2p f = (mp /(2L))2 (a/2) Ö (Y/r ) , where m .= 3, 5, 7, 9, etc.

and a=rod radius, L=rod length, Ö (Y/r ) = c = bulk sound velocity. Or,

    f = m2 (p a/L2) c/16 .

For an iron rod, c = 3600 m/s, and for a rod of radius 1 mm and a length of 1 m, we find

    f = 0.71 m2 = 6 Hz, 18 Hz, 35 Hz, 57 Hz, 85 Hz, etc.