Great info!
With punching the cartos- I use 100% VG so will definitely need two, maybe three holes. I'm thinking I could put a wooden dowel inside the carto, then drill with a pin vise. How big do those holes have to be?
You are creating a monster with those ideas and making the whole process much more difficult than it needs to be.
Anatomy of a cartomizer (click to enlarge)
You obviously don't know much about cartomizers. They are filled with filler, a tube, and a heating coil, so you couldn't put a wooden dowel inside of one. Take my advice and just purchase the laser-drilled cartos and save yourself a lot of headaches and frustration, and allow your tanks to live a long life.
Two laser drilled holes should be enough for 100% vg. If you have doubts, my blog has a list of vendors that you should be able to find a couple that sell cartos that have 3 holes drilled.
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tool-punched vs laser-drilled
The following is already in my blogs, but since you haven't had the opportunity to read them yet, I will do a briefing. Tool-punched cartos invariably distort the carto from a round object to being an oval object. This can make it difficult to put them through the very tight-fitting round holes of the tank's end caps. Inside of the endcaps are fragile rubber gaskets called 0-rings. Too much stress on these can cause them to wear out or tear, causing the tank to leak juice. Using laser-drilled cartos helps to eliminate this issue, and is why I recommend using them.
I also recommend in the blog to purchase a tank tool, such as the one in this video, to further protect your tank's o-rings:
