I use my sewing machine for three types of sewing, each of which uses a different type of thread: lingerie sewing (polyester), quilting (cotton), and freehand embroidery (rayon, polyester and cotton embroidery threads). Then I also have the odd bobbin of nylon monofilament for when I do applique and woolly nylon for lingerie. This can get tricky, especially if I have white polyester, white cotton, and white embroidery threads at the same time (which is mostly). I wanted a quick and easy way of keeping my bobbins and spools together.
A quick web search showed me that there is a cute gadget on the market called Handi Bobs which you can get at Clotilde or Nancy's Notions.
All I do is cut off a piece of the straw, plug it into the bobbin, and put the straw into the thread spool on my spool rack. The straws fit snugly into the bobbins, and just rest in the spools. Easy to do, easy to take apart, and no searching around if I accidentally drop one... I just cut another length of straw!