Makey, the Maker Faire robot mascot, looks great printed in glow-in-the-dark filament but is a bit lacking in contrast. By filling in some of the contours Makey looks much better, especially when it is glowing in the dark. I ended up mashing Sugru into some of the concave sections then wiping out the excess with my finger. A pin or needle works great for cleaning out any extra Sugru that may have gotten in between the print lines of areas you didn't mean to cover.
Rolling out Sugru into thin lines is a great way to make lettering. We added some flair to our bathroom keychains.