After cutting the hanging thread all the way back to the wound thread I place my bobbins into multi-sectioned small containers. I can put a few into each section....they don't move around and unwind.
I really like the idea of clear tubing as described above but haven't done it for a two reasons. No time (even though I'm sure it won't take long)....and besides - I'm not looking in my bobbins a long time that unwound thread would bother me and make me want to do it. Did that make sense?
On bobbins I already have wound up - I try to use them up when sew I'm sewing areas that won't show on the finished project. That way the bobbin container is kept to a manageable minimum.
Nan (watching the birds out the window on a BEAUTIFUL rain-free morning in NW Indiana)