I would like to know how to magnetize something - tin foil in particular.
Magnets? Tin foil is mostly aluminium which if I'm not mistaken doesn't magnetise.
If I were to offer any helpful suggestion it would be to research much more the efficacy of 'alternative' cures. There are many claims made particularly for products that are sold to those desperate for relief.
I think I'd steer clear of electric currents, not that they are dangerous, but that they need a constant power supply, which depending on the source used could be quite wastefull.
There may well be diet, lifestyle choices that would be more helpful.
So research, and intelligent scepticism for some of the 'amazing' cures available at a cost.
p.s. I had what I thought was mild arthritis in some of my finger joints when I started aikido, at first it was so painfull I thought I might have to stop. I persevered, it got better