Acrylic nails (gel might work too but I have never tried them). I don't know why this worked but I have also seen other people share this in here too. The downside outside of the cost is you can't keep them 24/7, 365 days a year though unfortunately. Well unless you enjoy paper thin nails and higher susceptibility to fungus for months afterwards. But without fail every single time I get mine I have absolutely no desire anymore to pick my skin. What's kind of odd is that without getting my nails done I hate nail biting and never engage in that behavior but with the nails on I'll kind of gently chew on the nails (think what you might do to a #2 pencil but without leaving marks) now and again but it's nothing harsh enough to damage them and I have no desire to do it in public. If you're someone who will benefit by just breaking the cycle now and again for a month or so I think this might work long-term. But obviously if you're looking for something to help daily this isn't an ideal method.