Another documentary post:

Fundamentals
ESL Howto: http://amasci.com/esloud/eslhwto.html
Another ESL Howto: http://sound.westhost.com/project105.htm
Triangular Cavity Modes: http://www.phys.ksu.edu/personal/wysin/OpticalModes/tripics/index.html

Supplies
HV power supplies: http://www.amazing1.com/profneon.htm
Graphite: https://www.alfa.com/en/gp100w.pgm?dsstk=40798
Material for frame/insulators and/or diaphragm?: http://www.canalplasticscenter.com/index2.shtml