Explain this concept to a Cujun!

[Bigshrimpin]

Another plus when using the 3"x3" squares is that you have minimal waste (from your 4x8 sheet) when using an expensive core material. Also laying out 3x3 blocks would seem much easier than measuring and re-measuring your dimensions before making long precision cuts to a 4x8 sheet of 1/2" marine ply.