Tattoos located beneath fingernails (and beneath toe nails) are
very rare (see link) but can be done. This Idea is about a
different way to do it, than the way described in the link.
First, think of how an old-fashioned dot-matrix printer works.
See second link if you need help with that.
Now consider the
fact
that your nails grow slowly but continuously.
So, at the tattoo parlor, the first thing you need to do is put the
finger or toe in a drill press. A very tiny drill will be used to
drill
a very small hole through the nail, but no further. We want a
nice
straight actual row of closely-spaced small holes, perpendicular
to
the growth-direction of the nail.
.
.
. -->growth direction
.
.
(dots represent holes, but they would be more closely spaced
than you see here)
Depending on the desired tattoo, the artist can now select some
of
the holes in the nail, through which to insert the tattoo needle,
and inject some ink. That's all for today; come back tomorrow.
The next day, since the nail will have grown a bit, the holes in
the
nail are no longer directly above the spots that were inked the
previous day. The artist can select some holes and insert the
needle and inject more ink. That's all for today; come back
tomorrow.
Eventually the growth of the nail will move the row of holes all
the way to the fingertip (or toe-tip), at which point the tattoo
artist is done
(if not sooner).
Enjoy showing off something that wasn't quite as agonizing as it
might have been!