Hi MG, this is the ” painter” of the cone 
I used non metallic acrylic paint as well as pigments and mica in glue for shine and interesting effects…No it did not sink in the plaster but stayed on the surface. This piece is to ” sing” by itself, because of the colours….no need for an electric cord. 
We have a cone of 27″ wrapped with a long cord (20 times). It seems that colouring the pieces gives it a boost because colours have their own frequencies that add up to the plaster and whatever is in there with it.
So if you and/or your students will paint their Plasterite pieces, see/feel what will happen 
. Have fun and I will post the other sides of that cone and other pieces soon.
OK my turn… Aright Steve give us a Bovis reading, I promise I will not ban you for that , My lady has gotten the ‘bug’ for the Plasterite and the decorating, so today we got bunches of molds and 75 pound of plaster 
, I know what I will be doing tomorrow ha ha
josh