Building the elevators is pretty straightforward. I will comment on a few things, however. First, make sure you double-check your measurements. The second photo shows how I nearly trimmed the skin wrong. Luckily, the error was caught early and no harm (or extra work) was done.
Lastly, the center rib is positioned blindly in each elevator half. The way I did this was to pre-drill two holes through the skin, then push the rib into place. With a centerline on the rib, It was easy to get the rib lined up perfectly. With a couple of clecos holding it in place, the rest of the holes went in with no problems.
NOTE: photos link to full size image