moldable plastic used in creating equipment prototypes

I had no idea this existed until a coworker mentioned it. It’s made from moldable plastic that you can shape by hand, and they say it doesn’t contain harmful toxins. I believe it would be great for building a prototype to check if dimensions are correct before spending money on the real deal. Any thoughts? Just search for it online… EDIT: I updated the post title because I discovered several brand names for this material: plastimorph, instamorph, and plastimake.