I was in our local beauty supply store the other day (source of free boxes and the cheapest acetone in town) and they were restocking the nail varnish.

It turns out the bottles are shipped in small boxes packed in bigger boxes, so I snagged a few of the small ones and brought them home. They come in different sizes and are ideal for storing loose tubes. This one pictured, for example, is divided into three compartments, each of which is the perfect size for an octal.

I now have a standing order for them to save all similar boxes for me.

If you buy lightbulbs commercially, in bulk, (yes, I do) you can have all the "free" boxes you want...