When it comes time to finish treads it is best to spread out the plastic drop cloth and set up your saw horses on top of the drop cloth, this is best to do in an outside setting. You will also want to set up a flat surface on top of the saw horses to place the treads on. Keep in mind this surface will most likely get covered in polyurethane. It would be best to use an air gun to apply... https://www.stair-treads.com/instructions-how-to/finishing-stair-treads-at-home.html