So you got a little juvenile Eastern BTS …. good for you.
Sand is not the best substrate …. for obvious reasons.
I take it the breeded exchanged licence details ( you'll need them to register the BTS on your permit / licence ). All you need is their AKL no , and their name and the town they are in.
I'd have the little skink on paper towels ( same stuff you in the pantry ) , a few layers of it in the watering , basking and feeding area of it's tub or tank.
I'd do 1/2 the floor out with just paper towels , replace these frequently, the food dish and water dish in that area, I'd have the water dish on top a suitable sized floor tile , the rest I'd put a mix of dried expanded coir peet (BRUNNINGS from BUNNINGS) and course Kritters Krumble , If you have access to gum tree leaf litter and shed twigs and bark they are great to add too ( adds nice texture to the bedding) , for a little BT juvenile , only need bedding deep enough for the skink to burrow through - they love It).
Keep the thick substrate dry for an eastern BT , and spot clean it if skinky soils it by removing the soiled bits..
Provide a VERY SHALLOW & WIDE WATER dish with water no deeper than 1/2 the thickness of the skink . The little skink will soon discover this water dish / bathing pond and will look after bathing itself .
The water dish needs a rough inside texture so the skink can get out easy.
Very young skinks shed frequently , and tend to shed all over all in one go , the very shallow pond will do the trick for helping it get the very itchy shed off itself.
If it's particularly badly soiled (due to the poor husbandry of the breeder who overcrowded the skink with it's siblings , then a plastic food tub like
https://www.decor.com.au/product/tellfr ... ong-2-0-l/ size 74 x 254 x 184 mm worked well for me with my baby BTS and works with hatchling bearded dragons and water skinks , can find these at Woolworths or Coles
or quick visit to the local Chinese for a take home meal and you'll get a few of these
http://www.richpak.com.tw/MS-750A.html?CID=8 , washed these are great baby dragon and baby BTS bathtubs.
Please don't bath it in the sink , or the people's bath tub . They are for people not for skinks , and the sound or the taps running with terrify the skink and if it gets away it'll land on a hard unforgiving surface ( tile or lino or concrete ).
I'd bath it on the floor or the bed or lounge or coffee table if it's necessary. Bath water temperature I find that works is 31 to 33 deg C .