The chalice is a smaller version of the cauldron as a representation of the eternal feminin and the element of water. We’re talking about a goblet, usually of the round type, in which we’ll have water represented during rituals, even though on ocassions it might contain some other liquid, for example wine during the simple feast.
The selection of the apropriate chalice is a delicate task. We could use a glass one, even though the traditional is made of metal: gold, brass, silver or the like. We must be very careful when choosing, preffering the ones with their inside covered in glass, silver or stainless steel, because metals like copper and brass can be poisonous when in contact with alcohol. We must also consider the size, preffering the middle-sized, to make it easier to handle. It’s not necesary to get a very ornated one; it’s perfectly valid to use, if wanting to, one of grannie’s crystal glasses, if we perform the appropriate ritual cleansing.
Shops specialising in wedding gifts are bound to have sets of two metal gobblets perfectly capable of handling alcoholic beverages (the ones that have problems when reacting chemically with the metal), and so can be a good place to find our chalice. Having an extra one can be useful if we want to perform rituals where we need both water and wine (or similar), and we won’t have the cauldron available or we’ll be using it for other purposes. Personally, I’d rather have two chalices: a brass one for solar celebrations, and a silver one for the lunar ones.
The ritual uses of the chalice centre mainly in being the holder of the chosen liquid, whether it’s water to purify the circle, or the chosen drink for the simple feast or ritual libation. Usually it’s use will be the first, and even if we can replace it with any glass, due to the ease of getting hold of one, I think it’s better to chose once and for all, and use the chalice regularly, not ocassionally.