I find it amusing that the NASA guys haven't heard of magnetic parts trays, or if not magnetic parts, then use a sticky mat........
The washer might be aluminum, so non-magnetic and could be lost. And it's a surpirsing thing, but things that are sticky here are not sticky in vacuum... We try to make things mechanically captive as much as possible when out used for EVA.
I'd imagine there would be some sort of safety tent or net in which they would work if they are working with small parts. A slight spring tension could keep it puffed out and out of their way.