Clean up buttons clearly
You put the buttons on a suitably wide, color-contrasting piece of paper and stick colorless adhesive tape loosely in matching width completely over the buttons. Glue behind the paper. So they stay together, you do not have to deal with cumbersome needle and thread and even if you have a lot of buttons, you keep the overview without threading and can keep all his buttons in a box.
If you always use the same size documents, you can literally "leaf" when needed, if you put them in a row. For round buttons you need a little more patience. Once thoroughly cleaned up, you have everything at hand.
