That would be a series of experiments in which the measuring instrument is affected by each experiment. Not scientifically sound but good fun I'd say.
Think bigger: each experiment affects the measuring instrument, but the instrument is reset over a period of hours/days. Therefore it is necessary to investigate in one order (stainless, soapstone, ice, ...), then rotate through the various permutations. Not a short-term experiment, but bound to be immensely satisfying.
By the time there's enough samples for statistical rigour, it would be a great deal of fun.