For what you are trying to do I would build a Flatmaster style sander with the side wings from Stockroom Supply. The wings will allow you to apply a light even pressure as you push the projects through, which will keep the thin pieces from flexing so they will come out flat. One of the problems with regular drum sanders and thinner pieces of wood, is the wood flexes from the pressure and, if the piece is not flat, it will come out exactly the same way, not flat. With the Flatmasterlight, using light pressure, the piece doesn't flex but it will still sand when you push it through, so it will end up sanded flat. That's why they call it the Flatmaster. The Flatmaster is not good for everything you will sand but if you want to sand pieces and have them come out flat, it does a great job.