One that can open to 150mm will be just large enough. This can be either a table mounting one with a clamping screw for fastening temporarily to the kitchen table, or a more permanent affair screwed to a workbench. It does not have to be good quality, I find my cheap thirty year old one that came from a gift catalogue is especially useful because it is loose and can hold slightly tapering objects like lute bridges! The jaws need to be lined with a small piece of wood on each side to prevent marking your lute parts., see the illustration.