There's a little welding, and I use Alumaloy in a few key spots too. The welding is at the tips of the boosters to complete the cones, the small spacer under the cone too. The radiator section is held together with long rods as rivets, but the center of that is all welded together. There's an internal structure connected to the main round vent which ties into the top part of the main center piece. All of that is welded together. There are welds holding the long vents together as well. I use the Alumaloy where the long center snout ties into the bottom center piece, and also along the edges of the flaps after I carve a V groove and bend the edges up to 90 degrees. But all the rivets you see are legit rivets doing what rivets are meant to do!
A few new pics. Working on upgrades to make the build a lot more accurate and a lot easier to reproduce the parts. These are cast in pewter. The nosecones I made by putting a huge chunk of plastic on the lathe and got it to the right taper. Then I made a fairly complicated two part mold that I was able to pour enough pewter into to force the pewter up the walls and into the right shape. The other parts are made by hand from aluminum, and then simpler two part molds are made from them. These parts are shown literally out of the mold, first try, without any cleanup done to them. I am also trying to cast the top radiator section, but I ran out of the mold material and I am waiting on new stuff to arrive before I can pour the second half of the molds. Even though my design is very accurate, none of the parts from the original plastic version are interchangeable. The boosters on the original are 7" diameter, and mine are 7.25".