You will need to make an angular cut at either end of the leg boards. 



Set the angle tool and use it to mark the angular cuts

Mark and cut along the lines.

Take 2 leg pieces. Keep them like an 'X'. Keep the top edges of the X against a straight edge from another piece of wood. 

Make sure the inner edges are 7cm apart as shown in the figure below.

Mark the position of the two 'X" on each other so that you exactly where to apply the glue. These markings are important because without it, the alignment of the top edges of the X-es will not be parallel. 




Once the markings are done, apply glue and screw the X together. 

Place the X on the base board, center it and mark the positions where the top edge of the X rests on the base board. Mark 2 screw points and screw the base board to the X. 


Tada, one leg of your base board is done. Now go make another one. Your finished leg should look like this - 



You need 2 legs