How to cut Hole for Stove pipe
Here is how I cut the hole for my pipe. Roll the cylinder for the stove body and assemble the stove with the two end plates. Position the overlap in the cylinder on the bottom of the stove. Once you have the cylinder with bottom down, mark the top dead-center on the cylinder. Also measure in from the edge the distance of the end plate offset +1/4". This point will be the back outside edge of the hole for the stove pipe. From that point, measure over
3" forward along the top edge of the cylinder. This point will become the front outside edge of the 3" hole. Find the midpoint between between the two marks, which is the center of your hole. Measure from the center to each side 1.5", which gives you four points 90 degrees apart on the edge of a round 3" circle.
Disassemble the stove and lay out the cylinder flat. Drill a large hole in the center of the 3" circle you have marked and use a scissors or curved aviation shears to cut out the circle. A sharp scissors will cut both the stainless and the Ti shimstock. You can also use a razor knife, but be careful because it will slip very easily on the metal. I used the razor knife. You could also use a 3" hole saw in a drill press, but be very careful because if it grabs as it goes through, you will have a spinning piece of shim stock with a razor edge that will cut anything in its path.
Reassemble the stove and hold the end of the damper or 3" stove pipe up to the hole you have made. It should fit front to back, down the top ridge of the cylinder, but not side to side where the cylinder curves away. Mark the excess material on the sides with a Sharpie. I then used a Dremel tool with a cylindrical stone to remove the excess material by grinding it away a little at a time. Remove a bit, and the refit the pipe to the hole. Note any place where it won't fit, and keep removing a bit of material at a time with the Dremel until the damper or the pipe fit perfectly in the hole. When you flatten out the cylinder again, you will now have a perfectly shaped oval hole.