You can order treated sand from large toy stores in Hong Kong. Another option is to look for places which offer treated sand to kindergartens. Do not use sand which feel like grinded rocks, particularly those with bleached white color. It is important that sand look like and feel like natural sand. We order sand from a company named Mothercare Online Shop. Price is HK$60 per 10 kg. We need approximately 15 kg for each tray. As for sandtrays, if you prefer to make them yourself, please refer to the set-up section. You can also order them through furniture stores. We order them through Ngai Shing Furniture in Shum Shui Po (Tel: 2386-1135). For each set costs about HK$1,600 (depending on the type of wood you choose). Note: HKSTA has no connection with the above companies.