I made myself one of these jigs using square box section steel. I used 25mm tubing with 20mm sliding inside (I think those were the sizes, I can check if you're interested). I needed to skim the inner box section slightly to get it to slide smoothly - easy when you have a milling machine as I do. An angle grinder would probably do the job, although more slowly and not so accurately. A bit of welding (angle section to hold the tool, and to weld on a nut to secure both box sections together). It was quite easy really, works very well when fixed to the stand of my lathe, and saved me some bucks.
Next job is to make an attachment to allow grinding of fingernail gouges - again I don't foresee any difficulties in making this.
I like making items such as these, because it's satisfying and saves me money. I can't make something like a chuck so I have to spend out, I've ordered one from Axminster, but when it comes easy stuff, well there's no competition between making and buying.
I shall try posting some pics when the jig is finished.
K