The technique is very high tech and sophisticated. In fact, I'm not sure I can safely disclose it. OK, actually, I basically rubbed it with my thumbs...
The cone had the advantage of being actually conical. So, I used Rocksim to print out a pattern for the wrap as a transition, which worked since the diameter at the tip was about .080" and not needle sharp. I transferred that to the tape (which required pretty wide tape) and marked the center of the bottom arc. I reasoned that if I made sure that the wrap was centered at a point on the bottom and I worked the foil up to the tip at the top, it pretty much had to be aligned straight. And I started in the middle and smoothed it with my thumbs as I went. The foil is soft enough to be pretty malleable, and will mostly smooth out if rubbed, barring any hard creases. Once I had the center on, I worked to one side and the other, like you might with vinyl and it came together accordingly. The seem runs aline from the tip down to the base of the cone, and I didn't have quite enough material (due to cutting error) for it to come back together at the bottom. But, since the cone had previously been smoothed and painted silver, its not real noticeable. I line that up with the rail guides.
It really went much easier than I was prepared for. With that said, I think that doing this on an ogive cone would be a lot more challenging - the foil isn't likely to stretch and comply in two directions at once like you might with vinyl.
