So I want extruded, right? I know you've told me before, but I forgot again
which is preferred. I need to keep a journal of all these facts!

Kinduva toss up for most hobbyists in some respects.
Cast is the preferred material for stress, aesthetics and bowing.
However,
Extruded is "easier" to work with for most hobbyists as it is more forgiving
insofar as edge preparation is concerned. Basically, because the stuff will
turn to mush easier - it's easier to get better looking glue joints. It is far
more consistent where thickness is concerned, and is cheaper. But it does have
a much higher propensity to craze and melts faster when cutting.

"ease" the corner? As in route the edge with a round-over bit so no wood is
actually in the seam?

yep, or simply tilt your saw blade and run it through the saw to remove this.

Post the link already! I'm happy to learn more.

still on paper, I bought the domain, have the host, just need to finish writing
the text and putting the corresponding pics with it. Now that I've actually
paid for - I'm much more apt to actually get it done
Working on it on a "sorta" daily basis ;-)

James