Here is a way that recently came to me for thinning a small piece of wood. In this case a piece of reversed kerf lining to fill a small gap.
Just position the piece on a flat sanding board with say 120G and use a small sanding block to move the piece back and forth. You can do a slight taper or wedge by varying pressure on the small block. It worked great. (For some reason my pictures are not automatically downsizing anymore so click on the thumbnail to get a bigger shot)
More stylish ways to do the same thing are welcomed.
