Had someone ask me yesterday how to 'print' onto the back of a piece that is to be 'printed' or textured on the front. There are 2 ways. I've illustrated using sculpy.
Method 1...do front and back separately then attach together:
Roll the two pieces of clay out separately on their textures.
Cut out the shapes and let them dry flat.
Put a wash of water on the back of each piece and press and 'squidge' the two pieces together, gently twisting them back and forth till they grab. When you then tightly squish them together and hold for about 10 seconds, a little of the self-made sludge will ooze out the sides. Leave it all to dry. After it is dry, file the edges. The bit that squished out will fill in the seam, and you should not be able to see it.
Method 2...Roll onto first texture, then press or roll the second texture onto the back.
Roll out first texture. Leave the clay on the texture sheet. Place the second texture face down onto the clay and either press evenly or roll on top of the sheet.
Remove the top texture sheet, then remove the clay from the bottom piece.
Cut out the shape....Voila.
You would use this method if you wanted to dry your piece over a dome shape. Using method 1 requires drying both pieces before attaching, so the 2 domes wouldn't fit neatly into each other.