Outcall Hot Stone massage
I do it, particularly in winter, but only with a few stones. I use the 6qt Spa Pro Stone Heater and have a HUGE belly stones, and another 5 or 6 pairs of large varying shapes in the heater, load the heater up with the stones already in it with no water, when I get to the client, It's turn on the heater and go fill the insert with the stones in it up with hot water. I turn the unit off about 15min before the end of the treatment so it has cooled down to an easy to handle temp to be able to empty the water out. It's an outcall massage with some hot stones.
If someone comes to me for a full stone treatment it is something very different - over 70 hot and cold stones used, with an 18qt stone heater and a cooler, rather than just 12 or so hot stones and a 6qt heater.