I would suggest using a scented wax melting pad:

Use a suitably-sized beaker instead of - or as well as - the ceramic dish. And, obviously, omit the scented wax! Be aware of the spark hazard associated with the power switch, and possibly use an infrared thermometer to check the temperature of the surfaces. If it gets much above 80°C on average, you could use fine dry quartz sand to disperse the heat (i.e. a mini sand-bath) - or maybe even some unscented paraffin wax. Beeswax, as you may be aware, emits flammable vapours when heated.