Foam is the structural material most soft puppets are built from — the skull, the jaw, the body, and often the hands underneath the fabricFabric is the outer surface of a puppet — the skin, the cl... More skin.
The word covers materials that behave nothing alike, and picking the wrong one is the single most common reason a first puppet comes out heavy, hot, and lifeless.
Reticulated foam
is the standard for heads. It’s open-cell with the cell walls burned or dissolved out, so it’s airy, light, and breathes. It takes contact cement beautifully and it sands to a soft edge. This is what you want for anything that goes over a hand for more than ten minutes.
Upholstery foam
is what the craft store sells you instead. It’s denser, heavier, and closed enough that heat has nowhere to go. It’s fine for a body core or a base you’re going to carve away. It is not a head.
L200
is a fine-cell reticulated foam that holds a crisp carved edge, which makes it the choice for noses, brows, and any feature you want to stay sharp under fabric.
EVA / craft foam
is a rigid sheet foam. It doesn’t compress like the others. Use it for mouth plates, tongues, and stiffeners — not for anything that needs to squash.
The hack: buy foam by thickness you can dart, not by the biggest block available. Most beginners carve a head out of a solid chunk and end up with something that weighs a pound and a half. A half-inch sheet, darted into a curve, gives you the same skull at a third of the weight — and the puppet still moves at minute forty of a shoot.