Here are two views of the same bowls. I used a turkey baster to place the different colours on the screens for the paper that was to become the  insides of the bowls, and for the outside textures, just pressed  damp mushroom pulp on the core of each bowl (which was made of  conk pulp). These were molded over glass bowls, on which I’d sprayed some Pam to act as a release. After sitting covered overnight, I put them outside in a shaded area until I could see the pulp wanting to shrink away from the bowl. With a little “nudge” from a knife blade, they popped right off. To keep them from warping, though, I left them sitting on the glass bowls until they were thoroughly dry.