High voltages can disrupt electronic equipment, so don't keep phones, pacemakers or other sensitive electronic devices near the supply.Take into account the sparks and corona discharges generate ozone, so use it in well ventilated areas. This voltage supply uses small capacitors to achieve a desired voltage, remember to safely discharge those capacitors by shorting the output when you finish using the supply to avoid accidental shocks (it hurts, but the energy stored in the 10nF caps is very small to be dangerous). Do not attempt to replicate this circuit if you aren't familiar with high voltages or intermediate electronics, high voltages are very dangerous.
This circuit is intended to be used for educational and experimental purposes (electrostatic experiences, franklin bell experiment, plasma generation, gas ionization, electronic igniter, testing of insulating materials.) this circuit should not leave the lab or your house, and it shouldn't be used to harm to anybody, human or animal.WARNING: Before you start making anything please take a moment and read this: