It's very tempting to use lowercase letters on pencils, but lowercase letters are really, really small and hard to read,  with the exceptions:

1) If the designated Large Fonts are selected which require the hexagonal pencils that can accommodate larger fonts and these pencils come in different colors with varying shades of ferrules so they don't easily make assorted color sets; and if

2) Really strong contrast between pencil & print colors is selected; and

3) The printing pane for text on a pencil is very narrow, and punctuation that is at the bottom or at the top is too easily cut off. It really is rarely needed.

So, what is really strong contrast you're probably asking yourself?

White print on the colors that fall in the middle and dark ends of the color spectrum.  

The middle spectrum colors will fool you into thinking gold print will work, but it is relatively hard to read small text with gold print on the middle spectrum colors.   Middle spectrum colors include:  greens, blues, purples, oranges, pinks, yellows.  But the Dark Green, Dark Blue, Navy, Brown, Violet, Hot Pink can use gold print easily with any sized font.

When in doubt, the rules of thumb for best results are:  go with UPPERCASE LETTERS,  white print and no punctuation for best results. 

I hope this helps.