A thin layer of latex was first poured into the mold to get all the details out. Then some of the same ordinary latex was whipped up into a foamy paste and poured into the mold. This foam is nothing near real foam rubber, but it does set into a spongy glob that is softer than latex that is set up in the usual way. This foaming trick doesn´t work with all kinds of latex. The one I used is Kryolan mask-making latex.