Here are a couple of ideas that I came up with as I was installing the U Channel and cat whiskers in my 53 coupe.

The first problem was when installing the U channel was to be able to affix it to the door with pop rivets but have the rivet head below the fuzzy liner. After determining where to drill the holes in the U channel I drilled them. Then I inserted a pop rivet through the back side, then inserted the home made "cutter" in my drill and then using the pop rivet as a centering device I cut the material out with my cutter. My pop rivet tool head wouldn't reach far enough into the u channel so I used a short piece of a threaded "standoff" to space it out. Sorry no picture on that. The end result was the head of the pop rivet was adequately recessed.

The second problem was getting the little "buttons" oriented on the cat whiskers the same as the holes in the door. I used a couple of clamps (left over from being used to install the headliner) to clamp the new piece of cat whisker to the old one to keep them aligned the same. The one trick I learned was that the reproduction buttons were slightly smaller in diameter. I expanded the buttons when I did the second one.