Divide and conquer!

1. Head to your local hardware store for strips of slim moulded railing for the square frames or wider pieces for the mid-wall dado and the picture rail (from $12.76 for 1.8m length, Bunnings).
2. Use a pencil and spirit level to mark out the size of your frames on the wall and ensure they are perfectly straight.
3. Carefully measure your moulding (the longer side is the actual outer width you want your frame), then use a hand saw and mitre box to cut your frame edges at 45-degree angles so they join at the corners.
4. Use wood glue to hold each piece of the frame level in place (use the spirit level), then use a hammer to nail each side to the wall. If your wall is already painted, pre-paint your cut frame pieces first and wait until they are thoroughly dry before using.