I think I’m the one you were referring to? (Pirate Treasure Chest)
@gernreich was correct when he said that Titebond III is food safe.
I don’t stain or dye the wood for any of my wooden mugs. I coat the interior of my mugs with a food safe Epoxy. I chose Epoxy over beeswax, shellac, lacquer, linseed oil, mineral oil, and others due to the ability to put hot beverages into the mug. Most of the other finishes will deteriorate quite quickly when exposed to temperatures needed for coffee, hot chocolate, mulled drinks, and other hot beverages. I coat the exterior with lacquer since that is supposed to also be food-safe.
one note, Sake cups are small, and when I’ve tried to make shotglasses using my slat wood technique, they tend to shatter when I go to round over the lip of the cup. Next time I’ll be rounding the edge over by hand vs a router.