At someone's house last week I saw they had made their own kitty litter box out of a large plastic storage box which had a lid, and catches at each end to secure the lid on. For a door,they had cut a semicircle out of the wall of one end, with the straight edge positioned about 10 cm from the ground which kept the litter in the box.

Hope this idea helps.

Try Truong Chinh Street in the south end of the city (go down Le Duan till you get to the flyover just south of Bach Mai Hospital. DON'T go over the flyover - turn right onto Truong Chinh. There are tons of animal supply shops (it's near the Vet college)

We haven't found any actual decent sized litter boxes here but bought (from Big C) a big baby bath for our cats and they are happy with that arrangement.

Maybe this will help ?

http://www.vetsinvietnam.com/

:)