is cheap – I bought 2 cork table mats for 2€, and they’ll last me a lifetime. Cork is easy to work with – You can shape it using your fingers, but once glued in place it is very durable. Cork is clean – Stuff you find in the garden needs to be baked to avoid maggots, rot, fungus and other nasty stuff. Cork
Following that I tend to litter the bases with bits from the bitsbox, to add some additional effects to the base.