Here you can see I am drawing out a block pattern on each wall panel. This will act as a guide for me while cutting out the mortar joints.
I used a rounded bit in my router to cut mortar joints into the polystyrene for the walls. I forgot to get a picture of a panel with the mortar joints cut earlier today while I was working. Iíll get a picture of the cut panels the next time I work before I paint them.