Leopard Gecko Substrate
What Leopard Gecko Substrate you should use is a very widely discussed subject. A lot of people have very different opinions about what
you should or shouldn't use.
Kitchen Paper Towel Roll Substrate

Great and very cheap option. Very easy to get rid of each week, very easy to clean up after, makes disinfecting / cleaning your "RUB" or Vivarium or Terrarium really quick.
Geckos don't try and eat kitchen paper towel so, no risk of injestion causing impaction. This was our favourite option when we were keeping and breeding Leopard Geckos.
Sand

This is one of the substrates which causes a lot of arguments. We can not recommend sand but, some Leopard Gecko owners like to use it due to it giving their vivarium or terrarium an
authenticate "wild" feel. The issues with sand are: Small geckos may try and eat a little of it causing impaction within their gut - that's at least a vet's visit to sort and can cause death. Sand is harder to keep disinfected - you can't clean every grain every week
to make sure that any bacteria in your vivarium / terrarium are gone.
Calci-Sand

Due to various experiences by people we know who have tried calci-sand, we can not recommend using it.
Wood / Bark Chippings

Very hard to keep disinfected - Far more so than with sand - leading to potential bacterial health risks.