why are wooden base and tin foil used in gold leaf electoscope? (tin is not used as leaves which diverge)

Tin is the conductor of electricity and can be used to make a thin sheets, therefore tin is used to make a thin light leaves of the electroscope. 

In gold leaf electroscope, when we charge the electroscope same charge occurred on the leaves and they repel each other,  if we use metallic stand then charge on the leaves will get affected but wood is the insulator to the charge there will be no effect on the charges on the leaves due to the stand.