We use these rings and heavy duty oak tags to keep track of color samples and formulas. This set is a DIY that includes 36 oak tags and a strong metal locking ring. 

Wind your yarns, threads or silks on the card, or staple a small swatch of your wool fabric, then on the front put the name of your color, on back put the formula you used or ratios. Very easy to keep organized, duplicate your colors or color plan a project.