I have always liked working with "plastic" materials.
As a child, like everyone else I knew I had plasticine. Unlike everyone else mine was always in separate colours. I also had modeling wax which whilst interesting was little use except for making witch "poppets"
Fortunately I lived near a stream with easily dug clay exposed in the banks. If you have every tried to gather your own clay you will realise that this is more difficult than it sounds.