During our time testing his perforator design, the Gcode converter
and discussing material sources, Spencer Chase pointed me to Uline,
a box company that makes very tough white mailers.

The mailers, it turns out, come in a 2- by 2-inch size, perfect for
piano rolls! Spencer was very generous and shipped me like 600 of them
so I have a supply of boxes 'til the end of time.

I highly recommend these compared to the usual piano roll boxes which
are nowhere near as durable or long lasting as these tanks of a box
are. They're not very expensive, either, and you can order upwards of
a thousand from Uline's website! https://www.uline.com/ 

I don't know where Tim Baxter and Julian Dyer are getting their
boxes from; if you want those black alligator skin ones then I suppose
they'd be the people to ask. But if you don't mind white ones with the
same flap design as early Capitol piano roll boxes (the maroon ones
with the lid of sorts) then the Uline mailers are the best solution.

They also have 3 by 3-1/2-inch by 12-inch boxes which should fit a
medley roll with XP flanges no problem.

These are the boxes I'm going to be shipping custom cuts in (yes,
they'll have labels -- I ordered 3000 of them, so I might as well use
them) so they should require only minimal brown paper wrapping because
of how tough they are to break (I'm not kidding when I say they're
tough: they're triple-ply or something and could probably get stepped
on and survive).

Piotr Barcz
Upstate New York