Even though I use high quality batteries and don't plan on stacking, it really does only take a minute to add/enlarge a vent hole. Doing so could save you a lot of trouble, even your life -- I think that's worth a minute of your day.
I have a metal tube mod that supposedly vents from behind the switch. I've always been curious if that was enough but have been too lazy to add more vents. After reading these posts, I took a few minutes and drilled an additional gas vent at the bottom of the mod.
While I have a Dremel, a cordless drill was my weapon of choice. You'll need a drill bit set... these can be found at most hardware stores for just a few bucks. I used a Dremel 628 7 Piece Drill Bit Set that usually runs around $7. Here's a quick step-by-step:
First step is to remove the batteries and set them aside. This is very important. If your mod can be disassembled further, I would recommend doing this as well. Next, start with the smallest bit you have and drill a small hole at the desired position. You may need to apply some pressure at first in order to get the bit to "bite" but once you're through the metal, it is smooth sailing. I started with a 1/32-inch bit (about 0.8mm) and incrementally stepped up the bits to 3/64-inch, 1/16-inch, and 5/64-inch. The final diameter came out to 2mm and it took longer to switch out the bits than it did to drill the hole.
Feel free to shoot me a PM if there are any questions. And if you're unsure if you can do this yourself, ask a family member, friend, or neighbor if they can do it for you. You could probably even ask vapor shops, hardware stores, jewelers, or mechanics for help... I can't see them charging you much, if anything, once you explained why you needed it done.
Happy (and safe) vaping!