75 cent fret crown tool
I first read about these about 18 months ago and went ahead and bought some birch and white ash 2" and 3" stock... and quickly proceeded to do absolutely nothing about it until yesterday (well, my workbench in the garage hadn't been working- or even benching for that matter.)
Bob the top-notch luthier from the North Bay had given my friend Felix a wooden crown tool like this but it was from a longer piece of wood and had a handle. "Handles? I don't gotta show you no stinkin' handles!"
So I cut a 3" piece from 2" stock and sawed a starter slot on the long sides of the block. The next step would be to put a piece of 320 sandpaper grit side up over a fret on a guitar and run the block back and forth until you have a properly shaped groove. The block is complete and you now hold a piece of sandpaper over the groove and can crown frets 'til the cows come home! The big advantage here is that you can shape the slot to match whatever frets you have on any guitar so after leveling the high ones you can recrown the frets to match the rest of the frets.
I took the process up a step by cutting a 5" piece of 3" white ash stock and using my fret saw to cut three slots the full length of the piece. I can now have 3 different varieties of fretwire on each side of the block so I can now replicate the crowns of 6 different fretwire sizes and shapes.
Here is a photo and link to the Buzz-Off® Fret Leveling Kit from where I got the idea...
P.S. If the fret tops are flat like railroad ties you should remove the "shelf" first with a file. I've been using a Nicholson 5 x 1/4" tungsen point file with the sharp edges and corners removed with a grinder to do that. Note the very fine double-cut teeth- just like expen$ive StewMac fret end dressing tool...
... and before using the crown tool I use my 600 grit diamond grit file (also with sharp edges and corners removed.)
I've bought several sets of them as the 400 and 600 grit files get worn out, especially if you dip them in soapy water for lubrication, but the worn out ones are still really cool as they have a much finer grit and scratch pattern.
They are great for spot-leveling frets as needed using fret rocker. I will slip one or two wooden clothespin halves under the strings to lift them up and those little puppies slip right in and get to work. I hold them at a 30° to 45° angle to the length of the fret, absolutely parallel to the fretboard. I don't just hit the hit spots as indicated by the fret rocker but try to keep the top of the fret as a perfect arc.
I then use the tungsten point and carbide grit files to shape the fret making it ready for crowning and dressing. BTW both of those files are great for dressing fret ends. Say goodbye to the mean old Mr. StewMac and hello to the wanton Amazon women...