For some items that need magnets installed correctly, I have a solid state one with red/green LEDs. Simple even after you've done 100 magnets.

I also have a sheet of the magnetic indicating film, green that goes dark where there's a field line.

One discovery, larger N42 magnets really like the stainless steel wedding ring I made. I can palm a magnet and then go latch onto my wife's ring...magic rings! Keeps her from running away, or is it keeping me with her? Whichever way, it works.