You can do several things. If it is completly square and you need it round you could start off by using a hand plane or a carving knife and trim it down closer to the right shape. You can make your own sanding block just by cutting a block of wood to the right width and then you can staple a peice of sand paper around the block. When the sandpaper is all used up you can rip it off and staple on a new peice.