My go-to fidgeting device is still an eraser. The important aspects for me are: * It's silent. * It blends in with the other stuff on my desk (although close observers might notice that I almost exclusively write in pen) * It gives slightly when I squeeze it, but I have to apply a significant amount of pressure. * I can rub one corner of it without damaging it or me. * If I accidentally drop it, it thuds rather than clatters.