Yes, it's another bookmark. But with a D20 on it!!!

Actually, I like to use small, useful prints when I'm changing filament colors to work out the blended period. We have enough bag clips (https://www.thingiverse.com/thing:45704) around the house, so I came up with something different.

EDIT (3/31/2019): I added a version 3 of the bookmark. I moved the D20 down a little bit and made it taller (3mm) to prevent the bookmark from cutting two grooves in the tops of your bookmarked pages.