well, i finally had a chance to build my armrest. here is what i did:
i cut a piece of aluminum 12" wide and bent it into a flat-bottomed U shape. i turned it over (open end down) and drilled a hole in each bottom corner. I bolted in two pieces of black phenolic (one with a 3-1/2" hole) to serve as a cup holder. then i figured out where the armrest should go on the center console to be comfy with my arm resting on it, and still be able to shift properly (and set the hand brake). I drilled 4 holes through the OEM console (!) and attached the armrest with 10-32 screws, large washers, and locknuts. I cut a one inch thick piece of foam to fit the top and stuck it in place with double-stick tape. I cut a piece of 1/4" thick felt out and wrapped the whole thing, using 3M 77 spray glue to hold it in place. Then a piece of black, grained vinyl was glued over all of it. I cut and bent a small piece of aluminum to act as a mounting location for my MIMA and FAS controls and screwed it to the under side of the top section after attaching the electrical goodies.
Thats about it. Fairly quick, not too dirty. and very nice to be able to rest my arm and get to my MIMA easily.
Here are some pics: