Random question of the day!

I'd like to make slime as a party activity for 7 and 8-year-old girls. Because of the timing of the party, I want this to go rather quickly, and prefer to have the girls just add mix-ins (glitter, beads, fragrance, etc.) to their own containers of slime that I've prepared ahead of time. Ideally, I'd love to let them each color their own slime, but am not sure if that'll work well if I make the batch ahead).

So.....does anyone:

(1) Have a favorite reliable, easy, big-batch slime recipe that I could make ahead (enough to fill probably 15 decent sized containers)? Must take mix-ins well!

(2) Have tips on mixing colors into slime at the very end of the process?

Also - favorite cheap but good take-out containers to send the slime home in?

Thanks in advance!