Right now I am working on a small project. I have a board (made of PVC) that is nearly 3ft long (1ft wide) and supported on each end. Mounted to the board will be various items. To save money and weight I am looking to calculate the minimum thickness I need so that the board can support everything and remain rigid without snapping/sagging/breaking. Unfortunately I am a little rusty from my college days in regards to how to calculate this. Any tips or help would be greatly appreciated.