What type of visa does a friend from Australia need to run a master cooking class in Thailand?

And with that good advice...I close commenting.

he is invited to give this master class, so the inviting company has to arrange the work permit and the documents for him to apply for the Non Immigrant B visa. There is no minimum amount of days you need to work inside Thailand or if your customers have foreign passports or it does not even matter if your customers are inside or outside Thailand. To work inside Thailand you need the Work Permit and the Non Immigrant B visa or in some cases the Non Immigrant O visa allowed to work in combination with work permit

As he is working in Thailand, yes he needs the correct visa. Contact his home country Thai Consulate for added information and visa application.

A Non Immigrant B visa applied for overseas, with documentation from a Thai company. Then , once in Thailand, he should visit MOL and apply for this: