Some of the guys have bought the building board from tower only to have it arrive with a warp, just a heads up. Some people like flat metal boards and use magnets instead of pins. I went to the hardware store and bought some soft pine, 12 inches wide and laminated another piece 8 inches wide for a 20 inch board. I have four braces under it to keep it from developing a warp. It works well for those of us still using pins. A flat building board is a must!! I take mine to the wood shop every year or two and run it through the plainer just to make sure it is still nice and flat. There are a lot of different types of building boards used, as long as it's flat and big enough for your needs your good to go.