I've got 75 year old home with gorgeous plaster textured walls that have cracks which I'm repairing. Question is, what tool(s) did they use to create the texture so I can replicate it. It's a smooth wall with below surface moon craters/pock-like indentations on about 90% of the surface. Can anyone help me determine how they got it that way? A rag doesn't match and a sponge creates above the surface peaks/bumps. These are slightly concave indentations with only slight peaks against an already smooth surface---again, like below surface moon craters. THANKS!