Don't spend your money on a corner trowel. If they were any good at all we would be using them in the field. You will never see one within 100 ft of a taper. Dp is right on about the durabonds. You never sand the first coat or the second. We do however after the second coat go over some of the ridges if any, with the side of the trowel. Third coat is thin. I add a little water to my final skim. Silky smooth and little sanding when finished. Been doing it that way for a long time and it works for me. You take what info you need from these posts and figure out what best works for you. Good luck