Around the house, wear snug latex gloves (such as doctors wear). They will allow you to do your usual tasks (or whatever). You can even work a computer keyboard with them on. BUT if you bring your hand up to your mouth to chew the nails, there are the the gloves as a reminder DON'T DO THAT. If you have the chutzpah, you can wear them in public and just tell people "trying to stop biting my nails." Or blow their minds with "just came from a crime scene." Even if you don't wear them when you leave the house, you will have started the habit of NOT biting your nails.