One time back when I had access to a very precise lab balance, I made up a series of check weights in 10, 25, 50, and 100 grains (two of each weight) by cutting and filing nails to length. I still occasionally use them over 50 years later. At the time I was weighing powder using an antique two-pan apothecary scale which had a slider graduated in grains (actually 0 to 15 grains in tenths), so I needed to use those weights for anything weighing over 15 grains. It had a little screw and nut device for zeroing the scale. I still have that scale but don't use it.