this. if you are serious about tuning your skis yourself, not just waxing, get a gummi stone and some files for taking care of teh edges and base. gummi stones are good for deburring the edges and making small detune adjustments, files are good for making more major changes to the edges, such as detuning right when you get them (i wouldnt recommend using files unless you have a good idea of what you are doing, just because you can take too much off pretty easily if you arent smart about it) if you are smart about it and only make minor changes with it at a time, it can be a bit more efficient than gummistones. i also like to use files for when you get a edge crack, and completely round out around a 1 inch section where the crack is so it doesnt pull out.
if you are unsure about using a file and how much to do, make small adjustments and toss a gummistone in your pocket when you go up, that way if you still want to dull them a bit more during the day you can.
also i know everybody here wont agree with my opinions for this. i have been tuning my skis myself for a number of years, and have found what works for me and what i like. once you are doing it yourself, it is up to you to figure out what methods work best for you