I love making textures for my metal clay work.
The other day I made a small pile of new ones. These are made using a two-part mold compound (I have used a product called Cold Mold, from Rio Grande, but there are other brands). Rather than carry the big pots around, I measured some out into some smaller containers.
I first used this stuff at a workshop I went to in 2011 (the second-to-last photo is from there) - basically you just mix together equal amounts of each part & then either press something into it, or it onto something. Once you mix it you have to work reasonably quickly.
This batch are fairly flat, more like texture plates than molds. They are all from either wood or concrete.
& then I've been drawing in my scratch-foam again...