So what I do is i get about 5 boxes of mix, 5 gallon bucket, put a little bit of warm water. Like 1/8 of the bucket. Pour 2 to 3 boxes in with the water. I have a drill and mixing paddle to mix. I like thickish slime. Remember, you can always add more water. Too much water requires a lot more mix and too watery is not gungey. I hope that helps. Cake and brownie batter is my favorite.
Mix it the night before because the raising agents will foam up and thicken the mix so you might have to add more liquid but stir it first to knock the air out of it to test the consistency.