I didn't like the push-fit design of other mini filament spool swatch designs, so I created my own design using 3D printed threads. The filament roll fits snugly onto the spool and is very nicely secured by screwing together the two spool sides.
The threads withstand a good amount of torque, enough to perfectly hold the filament roll in the middle.
I used a thermal printer to add 13x7mm labels describing what filament was used to print the mini spool.
In the print profile, you will find one plate for 4 different colored filament rolls and 10 spools, together with the rack shown in the pictures.