Step 1: The materials
A 2 litter soda bottle or bigger
A razor blade
and toilet paper
Sorry the last two arnt in the picture.
Step 2: The bottle
Step 3: The bark(or rock)
The next step is to draw bark shapes or rock shapes into your styrofoam. Then, cut along your lines.
Step 4: Put all together
Step 6: The texture
Finally, you are going to buy tile grout. A seven pound bag of tile grout only cost $9.00, very cheap if you're willing to go the distance. You will want the mixture to feal mix mustard when you stur it. Apply at least 3 outside and 2 coats to the inside.