AWOL:
And yet, there's probably one in that laser printer at the end of your desk.
True, but that one only has to charge up some dust, not produce big sparks.
You're going to be disappointed if you think you can connect 20 capacitors/diodes in a chain and produce an electricity show to impress girls with.
(I know I was... 
PS: Last year I became the proud owner of one of these: https://www.youtube.com/watch?v=z4wVveOvlqs