science experiment questions?

I wanna try doing some science experiments, but I have to know the answers to my questions first before I could do them.

making plastic out of milk:
1. can I use powdered milk? or does it only work on fresh milk?
2. at a website the guy used vinegar, and on the vid I saw in youtube the kid used oil? which one works better? ( or quicker? )

how do I make my own blacklight? is it easy? if I buy one, is it affordable? where can I buy one? <-- I dont buy stuff online.

lava lamp: can I use mentos instead of alka seltzer tablet? if I can, which one do I use? ( I mean the flavor ) <-- can I use the one with fruit flavor? or the menthol one?