I used a marmalade jar of 500gr.
The electrolyte is water with baking soda, on top I added some oil e.g. paraffin oil.
I surrounded the jar with a conductive foil, e.g. copper foil and the internal electrode is from copper but I added a piece of copper foil at its end to increase the conductive surface.
I can adjust the capacity of the glass capacitor by moving the external foil up and down
Decreasing or increasing the surface of the copper foil against the electrolyte.
The dielectric is the glass of the jar
I adjusted for 113pF
Best 73
SV8ANW