Greg,
You have exactly the right idea. In fact, I did an experimental maze carving in wood, and
found that the 90 degree walls came out too thin, and were often broken by the force of the bit
(about 1/16 inch or less in thickness). With a radius at the bottom, or a taper from a wider bottom
to a narrower top, there will be more cross section to hold them together, and to the remaining wood.
As for the issue of which is top and which is bottom, the software default is white high, black low, but
there is a handy button to toggle normal / inverse which makes it a non-issue (as long as you use the right one).
Thank you again for considering the idea. If it makes it in, it will, I think be very handy.
Cheers,
Michael