When Oliver Krohn isn’t using an Arduino to control the temperature climate chambers he is soldering SMD parts on hot sand! I guess the skillet and toaster oven is not cool anymore. 🙂 He is using a bunsen burner to heat the sand but anything would work as long as you can get the correct temperature. Might be a little hard trying to follow the reflow curve of some parts but in a pinch it looks like it should work well. I guess you could even get a really good temperature measurement by just jabbing a temperature probe into the middle of your hot sand. Oliver is tinning the pads with solder but if you started from cold sand or drop your board onto the bed of hot sand I am thinking you could also use some solder paste and place your components prior to heating. This might be a great backyard soldering experiment using a bucket of sand heated using a fresnel lens on a hot day.