Picture frames and boxes require joining two boards to create a right angle. The cleanest way to do that is cutting 45 degree angles at the end of each board, called a miter cut.

So, for a 30 x 45 cm photo – we're going to cut a 35 x 50 inch frame. Cut two 50 cm pieces of wood, and two 35 cm pieces. Cut a 45 degree angle into both sides of your 50cm pieces of wood to ...