casting resin..

[marajane01.livejournal.com]

i've checked through the memories on this, but didn't find exactly the information that i was looking for. What kinds of things can i put in resin when  use it, other than paper/photos. I'm assuming I can put glitter in it, but what else? Are there certain things/materials that I should avoid putting in resin?
Also, I'm looking for a cheaper alternative for the casting resin dyes they sell. Is there something else that I can use to color it, like food coloring?

Thanks in advance for your help.. I'll post pictures when I've completed my project!