Well, the very earliest stage of the makeup appeared as if by magic by changing a red/green filter from one to the other; the makeup in Frank's drawing was another matter. It's a brilliant makeup, one of the best horror makeups ever--and yet it's actually extremely simple. But it took a very gifted craftsman to achieve that level of simplicity and conviction.
Most of that is really March's face. The areas under his eyes are pulled down slightly with, what, cheesecloth? Some lightweight cloth, anyway, glued to his skin, which was then pulled down a bit and anchored. Plastic (or whatever) cones were inserted into his nostrils, apparently enlarged by dark greasepaint. He wore huge false teeth. The rest is greasepaint and some hair, plus a bushy wig. The very last stage, when he can't even talk any more, is more elaborate, but seen only briefly.