Been awhile since I posted anything. This project has taken a bit of a backseat to life. My original lampshade got a bit wrinkled, so I had a new one printed up at Office Depot on glossy poster paper. Need to mount it to some pressure-sensitive styrene to make it more durable.
Also, if anyone is interested in the dimensions, the original lampshade is roughly 28.28 inches long by 9.7 inches tall (should give you a 9 inch diameter lampshade).
The base of the lamp in the movie appears to be a 5 inch diameter by 3/4 inch tall round wood plaque that you can pick up at Michael's or some other art/craft store. Here are a couple of pics of the base that came with my original lamp (base needs to be refinished badly...). Based on screenshots from the movie, this looks like the right size and shape.
I think I found an exact match for the finial at the top of the lamp, too. Search around on ebay for "brass pineapple finial antique finish". Looking at screenshots from the movie, it seems to be a perfect match. The top picture is from the movie and the bottom is the finial I just got in the mail. Mine isn't lit from underneath in my picture so it's a bit tough to match to the movie, but I looked very carefully at this finial from all angles and compared it to every frame of the movie that showed if and if it's not a perfect match, then it's so close that I'm satisfied.
Now, from what I've been able to tell from the movie, the lampshade rotates at about 2 rpm. There are small AC motors on ebay at 2 rpm .
There is also an "inner" lampshade that casts shadows on the outer lampshade with the artwork. The inner lamp shade appears to rotate in the opposite direction as the outer lampshade. This is very similar to how old motion lamps used to work. Should be easy enough to get a transparency, paint some wavy lines on it, and roll it into a smaller shade to go inside.
Then cap it all off with a 9 inch translucent acrylic disc at the top of the lamp to hide the motor. I'd suggest using an LED bulb for less heat than an incandescent.