[knight_yyz]

You wind the pickup, gauss the magnets if they are non magnetic when you buy them. You can then pot them in wax or not...

Magnets have a strength rating. An A2 magnet is weaker than an A5 magnet with an A8 being the strongest of the 3. But a really really old A5 magnet could degauss itself over the years and be in the range of an A2. So you "charge" the magnets to your liking. Each one has a range.

 

[knight_yyz]

You can always 3d print a box or have one printed or just buy something off the shelf

Tons of arduino pickup winders on youtube

 

[knight_yyz]

You can get something printed on Thingiverse. I have had a few small projects printed for me through them