For sanding around rain gutters and the like, I do better with sandpaper than sanding pads. If you fold it over and crease it, you get a sharp edge that you can run along next to the gutter, without touching it. Since I can feel where I'm sanding with my finger, I think I have better control with the paper.
I think the problem is that the first three coats were not cured. If you put those coats on in rapid succession, you would have a thick layer of paint with a dry skin, but still soft underneath. When you sprayed one coat the next day, it was thin and dried quickly. As it dried, it shrank, and moved the paint underneath, causing those ridges. The good news is you don't have to strip it. If you wait until all the paint is fully cured, you can sand down the ridges, and add one more coat to cover. Edit: After looking at the photo again, you may have to strip it. It looks like there are a couple of blisters. Those may have pulled the paint up all the way down to the primer. If you can wait until the paint cures, it's still worth a try sanding it. If you don't want to wait, strip it.
To respond to your original idea, it would be pretty easy to cast mufflers in a simple two part mold. There are lots of good tutorials about resin casting out there. A word of caution: casting is fun and can be addictive!
I had a set. I sure didn't pay $1 for them, tho. More like 25 cents. They were a cardboard eyeglass frame, with a white feather, roughly shaped like the bones in a human hand, where the lenses would be. If you read carefully, the only claim they make is that you seem to be able to see the bones in your hand. Still a rip off, but I bet I wasn't the only sucker. It just occurred to me to check, but yes, you can still get them. From the same place I got mine: http://www.thingsyouneverknew.com/product/x+ray+glasses.do?sortby=newArrivals&page=4&refType= My Dad got us into this company when we were kids, because he bought stuff from them when he was a kid, in the 1920s. Apparently, selling junk is a good business model.
I wish I could oblige, Ed. Unfortunately, my little toy camera wasn't up to the task. I tried taking pictures, but the lack of any telephoto, and the stupid "digital delay" made it almost impossible. I couldn't get the timing down so that there was a car on the screen when the "shutter" went off. Here is the link to the group that was running: http://www.vrgonline.org/. Lots of pics on there. The event today is called the Jefferson 500.