I just finished making a magnetic field scanner and this is my first test of a guitar pickup. The pickup is a cheap single coil one - it does not have individual pole piece magnets like a Fender, instead it has steel pole pieces connected to a single ceramic bar magnet underneath the pickup. The first picture is a scan of the plane around 2mm above the pole pieces, I then flipped the pickup over and scanned it again. I did not correct for the background field or the misaligment of the X,Y and Z sensors.

In the graphs X is the long axis (0 to 100mm), Y is the short axis (0 to 30mm) and Z is the axis orthognal to X and Y. The field strength was around 150 Gauss at the top of the pickup and over 200 at the bottom.

I quickly found that scanning was the easy part - visualizing the results is the difficult bit. I need to add legends to graphs to illustrate the strength of the fields. I also need to combine X,Y and Z data to plot a 3D vector field.  I dropped the resolution down to a grid of 1mm intervals to improve speed. Next up will be more magnetically interesting pickups like Humbuckers, I can also scan a whole guitar with the pickups in place!