For round, square and sheet cakes, you don't need to cut a cake board. Simply buy a ready-made board that is 2 in. larger than you cake (For example, if the cake is 8 in. diameter, buy a 10 in. round board). Wrap board with fanci-foil.
For shaped cakes, cut a board to fit. Turn pan upside down and trace outline onto your cake board. Cut board with a craft knife, leaving 1 in. extra around outline. Wrap board with fanci-foil.