You can use wide butcher paper, an old sheet, or just about anything big enough to cut into a large circle. Fold it in half, then in quarters. Take a push pin a length of string and a pencil. Lay the fabric on the floor and stick the pin into the center corner. Take the string and tie one end to the pin and the other to the pencil. Now you can use the string and pencil as a compass to measure out the circle on the cloth. Cut the edges while still folded, and when you unfold it, you will have a perfect circle.
Mark the folds north, south, east and west. Now, just start cutting and gluing or safety pinning appropriate pictures and articles onto each quarter. Fold the cloth up and put it away when not being used for rituals. Or, you can hang it on your child’s wall and just keep adding things onto it. The more stuff on it, the better it will look.