I am wondering on how I go about adding weight when balancing for the CG and the wings. How do I add weight if I need to to the wings?

For the CG, I was just planning on measuring and drilling holes in a 2x4. Then insert pencils with the v tipped add on erasers to set the plane on and balance. Doing this for a 63" wingspan extra 300s.
1st plane I will be completing from start to finish. Just bought and flew RTF's till now.
So please shower me with your knowledge and tool reccomendations.