Cosplay Prop Help!!!!

(I legit didn't know any other websites besides here or Yahoo answers to ask this question)

So I wanted to make a prop drink (from the image provided)
And I wasn't quite sure how to go about it.
I was thinking about doing clear resin and adding food color.
should I go about it that way? a better idea.
At 2015 Colossalcon these cosplayers made the same drink prop but I cant remeber how they did it x__X

(Anime: Death Parade)