I found some plaster of Paris at the craft store, and divided it up into two quart baggies. I wrote the amount of water needed on the baggies and packed a plastic cup marked with a line to show me where one cup of water would be.
Once at the beach, I just pulled out the pre-measured bags and filled the cup with water and went to find a pile of sand that would work.
This was the tricky part. Most of the sand near the beach was too compacted and wet, and the sand farther away was too soft. I scraped up a pile of sand near us, and got Little Man to make hand prints.
They turned out alright, but next time I will add a little water to the sand to make the shape hold a little better before he sticks his hands in.
The second problem I ran into was that I was not 100% sure what the consistency of the plaster should be once I mixed the water in. The first batch was too loose and ran out of the indentations.
I used a little less water on the second batch and it was too thick did not pour well. I think once I play around with it and learn what the correct consistency is, this would work much better.
Also, it helps to have really clean sand that does not have shell bits or seaweed because everything in the sand stays in the plaster once it is dry. Next time, I will pack a sifter.
Overall, it's a pretty easy craft and I was pleased with the outcome for my first try. I think his grandmother will really like the hand print when Little Man gives it to her.