For large washers, I use a similar restraint. A piece of "all-thread" with a hook bent on the end so I can hang it. For smaller sizes, 1/4" and down. I use a "welder's" wrench holder. Basically a huge safety pin made out of whatever is handy. Coat hanger wire, brazing rod, even tie wire. I do have 1/4" and 6mm in bottles, well labled so I don't grab the wrong one by mistake.
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