Oh goodness, I forgot about updating this thread.
So here's where I got:
I finished a large amount of this, and, to a point, it did in fact work. It could roll. It could spin. But not well (either function). The mechanics I had worked out do in fact work. But the materials I would need for it to work well are probably non-existent. I would need something about 1/16th" thick that has perfect rigidity (no bending) and weighed next to nothing. If it exists, I'm too poor to buy it.
What I made weighed far too much (8-10 pounds, I'd guess) and when rolled, was about 8-10 inches wide. And I didn't even attach the bamboo to it.
So this is marked up to a "learning project" which, ultimately, did not work.
HOWEVER! I did provide a nice, huge version of the file with the complete map and spinning letters on it. I printed it out and, guys, it is gorgeous. At some point in my life I
will have glass-top coffee table with that map under the glass. It will be beautiful.
The one pic I have on my phone right now:
View attachment 96490