Yep, invest in a Wacom tablet and pen, bought my tiny 4X5 tablet back in 1997, never had to replace the nub (the thing that does the writing).  If you purchase the tablet, get a clear sheet of plastic (thick enough so it doesn't flop over) and glue the top edge to the non writing surface of the tablet.  Why, it way smoother than the tablet and prevents the nub from wearing down.  Are nubs available- yes, in fact a spare comes with the tablet.  The problem is that you lose the darn thing and when the nub get small enough to replace, you can't grab hold of the little bugger easily.  Jan