The 'rubber' feet can be replaced with suitable grey UK electrical cable outer sheathing, cut out with a paper hole punch, and glued on with Bostick All Purpose glue - at least that is what I have done with my PowerBooks, and they look, and the procedure works really well - no scratching the glass table, or the base of the PowerBook, and they are level, so no wobbling, just a nice stable, and not slippery placement on virtually any level surface.