i think i dont need to explain it its too easy,u can understand yourself. You can use these following things for whole circuit.i used diode bcz it stop capacitor to discharge by ur body.u will need these things
1. carbon rod
2. aluminum foil
Step 1: MAKING CELL
its so simple take one end of carbon rod and touch to ur hand and take one end of foil and touch it ur hand but dont touch carbon rod to foil.Now take ur voltmeter and check voltage across rod and foil,you will get 1v - 1.2v. Now if u press foil u will get more voltage,i press my foil and got 1.88v. i dont think i need to explain it.its so simple u can understand yourself.
Step 2: Upgrade
you can use a capacitor,diode for improve battery.diode for stop discharge of capacitor from ur body