The sharpening of the Nokogiri (Japanese saw). The owner of one of the regular tool store we visit sharpening a saw.
He's been doing this for close to 50 years (though he mentioned it's getting less these last 20 years). The hight of all the teeth are set level (the middle is made a touch higher). The straightness is checked. Any twists or bent is fixed by tapping the right place with the different hammers.
Next January, there'll be a workshop in Singapore.
It will be a 3 days course, starting with the crucial setting and maintinance of hand tools, and moving on to making a traditional Japanese joinery, the "Koshikake Ari Tsugi". I'll link the details in my story and story highlights.