I made mine years ago from 3/4 X 12 X 8 soft pine, lamanated two of them together so it was 24 inches wide, ran it through an over head sander then a planer. I added three cross braces cross wise on the bottom so it doesn't warp. Before every build I check it to make sure it is flat without warps. If it starts getting too much glue or epoxy on it I take it to my wood working club and run it through the sander. The pine allows me to use pins and it holds them very well. I'm seeing a lot more builders using metal tops and magnets for building these days.