This step really irritated me. The creation of the electrical channel covers should have been a last item in the previous chapter since it has to cure before it can be used. Second, I think the method described is much more complex than it needs to be. I followed the plans at first, then discovered that because of the thickness of the BID layer and the box tape on the plugs my covers were too tall. When you sand the foam in the LWX/LWY/longeron box to make it all the same height the electrical channel cover sticks out above it all. Then you have to jimmy in a bunch of foam around it!

Two hours wasted. I could have cut it down some but had already ripped it out in frustration and since I hadn't carved the foam yet I tried an easier alternative. You can see an original covers and the plug it was made from in the pictures below. Box tape doesn't stick well to foam, and BID doesn't stick well to box tape, so it was really hard to get clean corners, tops, and sides. I didn't. That method took two hours with all the work getting the plugs just right.

My new method went much better (and faster). I created foam plugs that completely filled the box, then carved the electrical channels into them. I left about 2" between the slants for an easy transition/mild bend. I then screed-sanded them to be level with the wood blocks using a long sanding block and a sheet of 50-grit. It makes a hell of a mess but it only takes a few minutes.

Then I turned the pieces upside-down on a sheet of plastic and laid up a ply of BID inside the channel. I let this drape across the flat section to cover the face of the foam that is exposed to the other/lower/outer half of the electrical channel (so I don't punch holes in it while running wires). Total time spent was 30 minutes, counting foam shaping. The extra layup at the top of one picture is just some BID scraps that were too small to use for tapes. I used some excess epoxy to lay them up in a small rectangle for some future use - maybe an instrument panel hole cover or something.

I did one thing really wrong, though. When it came time to trim the sides I found the the foam was short by 3/8". Nat said I could just 5-minute some foam back on and call it a day, so that's what I did. Phew. I did all the trim work but I didn't cut the holes for the spar yet - it's so easy to do with the Fein that I want to wait and make sure it's perfectly lined up.