I'm not sure how I got caught up in 2 different threads on the same exact subject but will post this in both.
So I take the dremmel approach. What isn't explained well in Phils video is that you basically need to more or less shave a hole into the cart during the back and forth motion that he shows. I shorted out 2 carts because I just cut into them rather then "shaving" back and forth until a hole is revealed.
So I have a 2.5 dual coil and a 3 ohm boge each with a "small" hole on each side in tanks and using them and they both are producing air bubbles. Now when I say small hole, it seams small as you do it but to compare it to the tiny hole in the smoke tecs and it's rather large.
All is good so far, I have to see how they do in the long run.
When you do this, have a good light and a magnifying glass couldn't hurt either.