that would be me with the large pebbles and by large i mean large so you need two hands to carry one of them, they are put together like a patio with coconut fibre in crevases between them like grout so no no holes or gaps, i did use small pebbles for my fire bellied toads when i first got them but changed this very quickly as crickets actually hide inbetween smaller pebbles easier plus small pebbles is definately not a good substate for a gecko every time it strikes for food its likely to swallow some pebbles aswell....definately not a good idea...
just so you get an idea of size i mean..i have since updated this so even more stones and less coconut fibre..
but i would say kitchen roll for up to first 6 mths is best, also you should'nt really just tip in food so that your likely to get loads hidding especiallly when gecko young, i tend to drop one in at a time when thats caught and ate next one etc, if you just pour them all in at once while shes chasing one others all have plenty of time to hide and as crickets bite leaving them in viv overnight is not good...