Just like other rodents, hamsters need a sand bath to keep their coat and skin in good condition and to clean off excess oils. Sand baths should be permanently kept in their cage and sifted through daily to remove any toileting. Some species need larger sand baths then others. Syrians and dwarves do well with a large container whereas Robovoroski hamsters need a larger portion of their enclosure to be sand (around 1/3). If your sand bath is quite large, try adding a hide to make them feel more secure.
There's lots of options for sand-baths, from bought sand baths to using everyday items like glass oven dishes and sandwich containers. Good examples of safe sands are calcium-free reptile sand and children okay sand that is baked and sifted before use. Sand with added dyes, chemicals or other ingredients such as calcium or clay should not be used.
There are some great examples of good sand baths that you can use (list below) but they don't necessary have it be expensive and you may already
have something suitable to use at home already like a glass or ceramic oven dish.