There is food-safe filament for 3D printers but it isn’t ABS. I just wouldn’t do it at all, indeed like you said for the layer lines creating perfect spots for bacteria. But also because most of the filaments or plastic used for filaments are made in China and they tend to use harmful chemicals to cheap out on production or their machines are covered in bad chemicals for lubrication for example, ending up in/on your filament.
There is food-safe filament for 3D printers but it isn’t ABS. I just wouldn’t do it at all, indeed like you said for the layer lines creating perfect spots for bacteria. But also because most of the filaments or plastic used for filaments are made in China and they tend to use harmful chemicals to cheap out on production or their machines are covered in bad chemicals for lubrication for example, ending up in/on your filament.