Mal-

Your query aroused my curiosity about finger/box joints (I've always
thought of finger joints as those joining lengths of wood as putting your
fingers together parallel and a box joints as those joining at 90°).  As
Mike points out, box joints were used as a quick way to make a box with
machines, no surprise there, but that type of joint has existed for much
longer than tailed tools have been around, assuming you believe what is
written on the internet.  Somewhere I found one reference that such joints
were used by the Egyptians.

If I was to set about doing such a joint by hand I would approach it the
same way I would a dovetail, lay out a base line and mark out the "tails
and pins".  A hand cut box joint wouldn't need to be regular as a machine
cut joint typically is; the tails and pins could be random widths, but I'm
guessing you want to replicate the machine look so I'd set off the widths
with a divider to the desire dimension.  Pare/saw out the waste.  I think
I'd still use the first cut board to lay out the second so the fingers fit
any irregularities resulting from the handwork.  Glue them up and trim the
finger tips you intentionally left a tad long.

I started into this thinking cutting a box joint would be easier to do by
hand than dovetails, but now I'm having doubts.  A box joint to replicate a
machine cut one needs a high degree of precision and uniformity, something
machines are pretty good at.  Creating that uniformity may be a greater
challenge than creating the hand cut look of dovetails that so many prize.
I'll be interested to hear your thoughts after you've gone down this path.

Phil