Ok I am going to see if I can post a picture. I got my old cabinet from the airport and brought it home. This was to be kitchen cabinet but it came out 1/8" out of square so I built another. I kept this one for my hangar. I checked the top and it was almost one string width too high in the center of the long span. The cross span was flat. I shimmed the right side and added three screws to the center. It is now as flat as I can get it. I checked it with a 5' scale, 1"square aluminum tube and finally a 1.75" square steel tube. You cannot slide a sheet of paper under any of these instruments.

So I cut my sheet of melamine 30x77". This sheet weighed a ton, I struggled to get it ready for cutting. I, then, placed the cut sheet on the cabinet top and remeasured. Again, flat as a pancake. My question is can I get away with leaving it as is, just tied down on the perimeter? I had intended to use the 1x lumber to build a frame for the melamine and have it adjustable for flat as jester mentioned. I could build this plane and do the frame later. Or is it best to do it now?

The drawers have come in handy as I am starting to gather building tools. The shelves behind the door will hold some balsa stock. I may cut some foam to protect some from the heat. I have a good supply of old lawn mower blades 1/4" thick. I am cutting them and use them as weights. Should prove to be good. Right now I am using pieces of railroad track that I have.

BTW, somewhere in the back pasture will be a test pilot grass runway. There I will crash uh uh I mean fly my plane.