@Jacel @starkatt my solution:
* get white bedsheet set (black would probably work great too) and glow-in-the-dark paint
* lay out bedsheets and gently spatter gitd paint to make star effects (and then let dry)
* tack bedsheets to ceiling
it worked pretty well for me! I need to do that again--my original starsheets are pretty ratty by now, but I should be able to get new sheets and paint easily enough, and I miss the star-tent effect. :)