Thank you all for your comments. The Sharon Schamber video was especially helpful. I decided to use the cotton duck. I know that the silver cloth would be a good choice too, but I already had the duck and didn't want to buy new supplies. I finished making the pillowcase for the top today, and my daughter helped me pull it onto the board. I had intended to close the open end with Velcro, but I decided just to tuck it under instead, at least for now. The duck did shrink - a lot! - when I washed it.
Don't look at all that mess on the cutting station behind the dresser. I'll clean it up, I promise!