
I use a combination of purchased markers and handmade labels for 2 main reasons: convenience and necessity.
The quick, laminated, handmade tags were constructed of cardstock with large, contrasting, Letraset numbers. I made a number of these for needle sizes for which purchased tags didn't exist. If you used a circle punch when making them, they would look more uniform.
The molded, plastic tags are available from Knit Picks.
1) Small diameter needles are too tiny to display the size.
2) I have needle sizes for which I was unable to purchase markers.
3) When using cables to hold work while the needles or needle tips are deployed to another section or project. This way when I return I know what size needles are needed to complete the work and maintain the correct gauge.