I have a standard plastic ruler which I have been using for a couple of years and through general use the edge has become not so smooth and quite bumpy.
This is somewhat unhelpful when trying to draw a straight line, so I was wondering if there was any way of restoring the edge of a plastic ruler?
I imagine it could be something like sharpening a knife blade but I am not sure how I would be able to make sure that it remains straight and doesn't become wonky.