Magnet implanted in toe
The magnet is 6 mm diameter, and spherical.

It was implanted under a callous in a standard way by myself as a "trial run" before implanting a normal magnet in a finger.
It was sealed with superglue instead of sutures.
I cannot take any pictures because I have no camera other than a tablet, and that is no good.
Implantation day: Shoe insoles or very thick socks are needed to be able to walk any good distance, burns constantly.
Day 1: no pain unless I put pressure on it; was able to feel some things with it; played with it and picked up a 2 pence

Day 2:same as day one
Day 3:had to remove it (maybe unnecessary), the skin holding it in popped back open.
Tagged:
Comments
it's good enough for showing where exactly you cutted into the toe. Also I agree with @Cassox - pics are important even if they don't show much / don't have the best quality and updates on the healing process is a must. :)
@D_Axel sweat should be sterile, it's just the fact bacterias love warm and wet places that such feeds tend to smell. As long as he cleans it good enough infection shouldn't be a problem. Anyway, keeping the wound dry might be. Walking with bare feeds could help a lot but not everybody likes that and you can't do it anywhere (at work, for example).
@MagneticJacob I know this isn't a question most people want to answer but do you have sweaty feets and if so: How do you fight against it (if doing anything) while the skin heals?
Another thing: You mentioned the need of very thick socks, so there seems to be a lot of force on the incision point? Is it placed on the side (so another toe pulls on it) or at the bottom (so your bone is pushing - note that this would be a no-go as (IIRC, somebody please correct me if I'm wrong) bones get smaller when there's something rubbing directly onto them for a longer time). Also aren't the socks itself creating pressure? Ofc. you could also answer these questions with pictures... ;)
To answer your question though, placement should be subcutaneous or in/beneath the hypodermis. The hypodermis kind of "pulls up" from the underlying structures. It would be fine to place one in a touch of adipose tissue or something if being placed where skin is thick. In the fingers, the actual amount of hypodermis is minimal at best. You really can't place it within, only under. Same goes for the bottom of the foot.
It is currently day 4.
The benzocaine cream just dried out too fast, that os why it did not work last time.
The worst part about it is the fear when a rock actually gets in my shoe, I think that the magnet popped out.
I will make a picture when I get a chance.