Wheel truing has beguiled me in the past. The only way I will ever get comfortable with it is possibly getting some wheels to practice on. I tried to true one of my wheels once without having practiced, and it was never quite the same.
Reader Pedorro obviously takes his wheel truing seriously, and the following hack he submitted proves it.
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Construction time: 10 minutes using Metal Devil blade
tools: stick welder, circ saw with metal cutting blade (recommend Morse Metal Devil about $50)
dial indicator on magnetic base, can be purchased from Harbor Freight for about $40
~16" of 1-1/2" x 3/8" steel bar
~16" of 2"x2"x1/4" steel angle
Use circ saw to cut dropout in one end of steel bar (no need to be precise, but make it at least as wide as your largest axle) and then cut other end at 45 degree angle.
Weld 45 degree cut end of steel bar to steel angle about 5" from one end.
Mount angle in vise, clamp wheel into dropout with qr or nuts, clamp mag base to angle, position dial indicator for horizontal or radial truing.
45 degree angle on bar puts wheel over bench and puts dial indicator in convenient spot for using spoke wrench.
The picture says it all. It works on all sizes of wheels, you just move the dial indicator, you can put the dial on both sides of the rim, you can use the mag holder arm for radial truing or make a wide roller for that, you can even true disc rotors. The dial indicator takes all the guesswork out of lateral truing, it's really easy to get the rim within 0.01" in a couple passes.