Alginate

Alginate is a skin safe powdered material derived from algae and is often used for lifecasting molds of hands, feet, heads, and other body parts. Alginate molds usually are only used once because within a couple hours, the mold begins to shrink. To make an alginate mold, the powder is mixed with water to create a paste that is spread over the surface of an object. An alternative method is to submerge the object in a container of alginate as shown in the video below:

https://www.youtube.com/watch?v=ES6BOZ-N9dM Links to an external site.