Re: Constructed vertical writing systems?

Glad to hear that you're interested in vertical constructed scripts!  (Which
cannot be abbreviated like conlang, obviously.)  I'm interested in writing
direction in general, myself.

But about vertical scripts specifically, I second the earlier suggestion
that you check out traditional Mongolian.  It's not only my favorite
vertical script, but my favorite writing system of any kind.  I think it's
the most beautiful script ever created...

In my own conworld, I've got scripts that go a number of different ways.
Several are top-to-bottom, left-to-right, like Mongolian.  Most are either
right-to-left, top-to-bottom, like Arabic, or left-to-right, top-to-bottom,
like Roman characters.  A few are boustrophedon (as the ox plows), meaning
that they go from one side to the other, then back again, one line being
left to right, the next being right to left, etc.  One of my conscripts is
often written in an outwards-going spiral, but none are written bottom to
top yet...