@toro He made soap. He wasn’t exaggerating, the caustic stuff can really kill you. Castlie soap is made with olive oil but you can make soap with any oil or fat mixed with a lye/ caustic soda or sodium hydroxide all of which are deadly if not handled correctly. Homemade soaps take a while to solidify then about a month to cure, or else that are very harsh on the skin and the soap is very soft.
Homemade mayonnaise is just egg yolks mixed/whisked with oil and maybe a pinch of mustard and a tiny bit of vinegar to stabilize the emulsion. It’s really easy to make as long as you have the arm strength to whisk or a food processor
But as someone who has made both homemade soap and homemade mayonnaise, he’s right, making your own does become an addicting hobby