You will need a 15 cm ruler, your set of mathematical instruments (protractors, compasses, set squares etc) and a pencil beforehand.

I used pen for the main working lines so that you can see the lines more clearly and pencil for the ones which a pen would not permit due to incompability with the instrument used (the compass in this case).

Let me know if you need more explanation. It is hard for me to explain this online since I always explain this to my students face to face.