After priming and sanding and priming and sanding, here are the parts ready for some gluing. First the centering rings go on the front of the rear body tube. I also re-drew the fin lines. To align the finlets (the small fins which are called “dorsal fins” in the instructions, apparently because no one at Estes knows what the word “dorsal” means) I tried this scheme: Using removable double sided tape I stuck a small finlet and a large finlet, aligned along a ruler to the correct distance apart, to a scrap piece of balsa: Then I used the Estes fin guide to glue both at once to the airframe: And it worked… fairly badly. I managed to get two finlets aligned parallel to the body but a couple millimeters or so too far back, and one or two more were canted, and one or two were not really up against the airframe… in the end I resorted to Eyeball 1.0, with better results.And by the way, there’s an error in the instructions. From the pictures for these steps it’s not obvious whether the larger finlets are in front or in back, but it says to put the J finlets at the rear and the K finlets at the front, and in the illustration of the fins earlier J was the smaller finlets, K was the larger. That’s wrong, though, as is clear in the face card picture and the picture on the front of the instructions: The larger finlets should be at the back.