Fill a powder free latex glove with water or whatever liquid you would like to melt into your punch and freeze it. Not as great as the brain molds I used for Brian's party, but better than just regular old ice!
Creepy Treats for Halloween
Brain with Blood Clot Cupcakes | Annie's Eats
25 Amazing Plants vs Zombies Cakes | Walyou
I bet I could use this method of mold making to make pea shooter soaps!