I may have mentioned this already. Please forgive the repetition if I have.

Most thumb picks come from the factory with much too much length for most people. Common every-day nail clippers will trim and shape a thumb pick well. A little filing and fine sanding will round the edges. The best and most commonly available abrasive for an absolutely smooth picking surface is likely toothpaste, but I don't personally find it necessary.

Peace, Mooh.