Enlist bleach pens to make a starry backdrop for your vows or to monogram reception napkins.
To craft a ceremony marker that's out of this world, lay a dark blue length of cloth (we used Grayline Fabrics' "Barry" linen in navy) on a protected surface, and, like you're wielding a marker, (dis)color on dots with a Clorox gel bleach pen ($3 at drugstores). Start slowly, periodically stepping back to survey your handiwork to avoid randomly overpopulated clusters. And vary the size of the "stars" to look more astrologically correct. Once you're happy with the state of the universe, let air-dry, and then run the fabric through a soap-free rinse cycle.
The details: Theia gown