AusBonsai

Over time I have been growing ficus, chilli and adenium trees and recently saw a ficus that was very unique it is the type that has lots of tangled big roots (tubers) and I am wondering how they get the roots to be tangled and bulged like that in under a short period of time because the one I saw was 3 years old but there were three or more big roots that were at least as thick as a coke can so I was wondering how to do it
Thanks, Ficusboy