I was unhappy with the swatches and cases here on Thingiverse... so I made my own! In addition to making my own, I wrote it as a Customizer, so you can make it your own too!
The included download includes swatches that are 80mm x 30mm x 2.3mm. It also includes a default box kit that will hold 30 swatches of that size. The reason I chose that size is because it's about the size of the standard Avery address label. In addition, there is a cutout on the front where you can stick on a standard Avery return address label.
However, with the Customizer, you can make your own box kit. You can increase or decrease the number of swatches the box will hold, change the distance between each swatch, as well as put your own custom text on top of the box. If you wanted to make your own swatches of a different size, you can even change the box kit to fit those as well!
Dare I say it, this may be the last Swatch Toolkit you'll ever want to use!