[youtube=”http://www.youtube.com/watch?v=K3G2QM5a-9U&feature=youtube_gdata”]
Piezoelectric materials are about as close to magic as you can get. They turn physical pressure into electricity and can even turn electricity into physical pressure — an amazing sort of bidirectional converter for mechanical and electrical energies. Perhaps even more amazing is the fact that you can easily ‘grow’ your own piezoelectric crystals overnight using just a couple of common ingredients — awesome.