So my existing shrouds didn't quite fit over the centering ring, so I made a new one (single layer) and it was *perfect*:
You can just see the edges of the paper on the outside of the ring.
I also decided that the transition that was really most vulnerable to crushing was the big one in the rear, because it has so little curvature there's very little strength gained from its shape. So I made a double layer, and thought it looked great.
Next day I came back and noticed that the two double layer shrouds had puckered quite a bit from the Titebond II. So, lesson learned: don't laminate shrouds with a watery glue. Both of those shrouds went into the circular file.
Finally, I had already printed a couple more of the front shrouds on the cardstock, so I figured I might as well make it. So I made a double-layer, this time using a glue stick, which was the only glue I could think of that absolutely would not pucker the paper. Normally, I trust glue sticks about as far as I can throw them (although I could probably throw one pretty far...), but I gave it a shot anyway. Indeed, the adhesive qualities of the glue stick are almost non-existent, I don't even know how anyone does anything with them. But after tacking down a couple of loose corners with Titebond (just a tiny amount), it actually looked OK. No, better than that: it looked perfect. And strong. Here it is in the drying rack:
So I decided to use it. Before gluing it on, I needed to mark the fin lines on the BT55, lined up with the ones on the BT80. I made a little paper template to help me line them up:
And then, after marking the tubes (and removing the paper template), I glued the shroud into place. It fits perfectly and looks very nice. I still need to fillet and smooth out the edges, but it appears to be a success.
In this picture you can see that the seam on the shroud lines up with one of the fin lines, where it will be covered by a strake.
And thus ends the shroud-making saga, at least for this rocket. I'll feel pretty confident with these things going into the next build (I'll need one or two for Starship Avalon).
Oh, for the rear transition I decided to stick with the shroud I made originally (from the posterboard), and just be careful with it. I don't feel like making any more.