First one is the empty tube.
Second...I took a red marker and marked the seam line all the way down the tube.
Third...I took a blue marker and marked a second line between the first line all the way down the tube.
Trust me there is a reason to my madness
Fourth... I took a large metal skewer with a handle on it, called a gimlet. (It came with my microwave).
Jabbed a hole in at the red line and out at the blue line keeping it straight.
Are we confused yet?
I did this all the way down about one and a half inches apart.