Minimize warp in long narrow door

Rich - plywood isn't the same thing as the laminated boards that Oughtsix is talking about. Plywood layers are at the very most 1/16" thick. Plywood in general is made up of crappy "filler" wood that is used in the inner layers that is full of holes, voids, mismatched pieces, etc., you aren't going to have a strong product. When the layers are that thin they also aren't going to prevent warping as we see in much plywood that is sold today. If you take 3/8" thick layers and carefully match them so that the warping tenancies are back to back, then clamp them on a flat surface using high quality glue, you are going to have a very solid and stable piece of lumber with little or no stress to cause warping. Why do you feel that you have to argue with almost everyone on almost every subject? This is a woodworking forum where we share ideas, experience, wins, losses, and solve problems. It's not a debate forum. Don't be the school bully that nobody likes and everyone fears. Everyone has their own opinions and experience that has worked for them. It may work well for someone else also. There are multiple ways you can get to the final result that are acceptable and will work for people based on the tools and materials that they have available to them.