Well if it's as big as 10 inches some type of plastic storage tub with a door cut into it would work or a small house made from wood. Tupperware if its a hatchling, even a shoe box. Hope that helps!
I use large flat rocks (and a little mortar to join 'em) to make caves in the outside enclosures, but you could do the same, inside...for inside hides using small flat rocks (under 12"), silicone glue works OK, and keeps the weigh down a bit.: