Not the marble variety, but a good old stone mortar and pestle of a large size, will be very handy when making Thai cuisine. Thais use this for grinding pastes, milling rice, creating relishes and a host of other handy uses. A mortar and pestle let you mix curry pastes without water, as opposed to a grinder, to which one needs to add water to bind the paste, thus making it more watery and less flavoursome. Try to make your ingredients from scratch, such as the curry pastes and such as, the curry pastes and coconut cream, and you will be a raved about 'Thai' cook at home.