OK, the bottle is going outside the fridge, taking up too much room. Not so much the bottle, but the regulators etc etc. Plus all the hose… Too messy. And there’s some other reasons.
Sooo, I want to put it off to the side. Drill holes JUST smaller than the diameter of the CO2 hoses, nice tight fit.
Has anyone EVER heard of freon lines in the sidewall of a fridge? It’s a Kenmore fridge up/freezer down.
In a modern fridge you’ll be fine. That’s exactly what I did. (is there a disclaimer button) 
I was under the impression, at least as to mini-fridges, that the lines are in the sidewalls and there’s a cross-over line on the top.
As to a full-size fridge, I do not know. But I would suspect that it would be similar.
I would use caution and research before drilling.
I AM researching… It’s a full size.
I did exactly what you’re asking. There ARE lines in the side of my 18+ cf. Kenmore fridge. A single line on each side that run diagonally from the back/bottom to the top/front of the fridge section. I found a diagram on the bottom front of the fridge, back behind the plastic louvered cover on the bottom. It showed these lines. Just to make sure I carefully drilled a very small hole on the inside & fished around with a piece of wire to see if there wasn anything more than insulation. Once convinced I carefully drilled a little bigger hole & visually inspected it. Then I drilled the hole with a step bit. I used a couple grommets (inside & outside the hole) to fish the CO2 line through. YMMV… Cheers!!!
AHA! I knew it…
No more diagram…but, Sears is pretty good about stuff on line…good idea.
+1, Fish through the foam first.
Yeah, that’ll have to be the way. No luck finding a schematic for a 1068679381 Kenmore.
I used rubber grommets to put the vinyl hose through. Didn’t want the wall to gradually cut the hose.
Why not just cut out a bit of the door seal? Just enough to feed the hose through and maybe a dab of caulk to hold it in place. Run the hose from the back and under to the corner by the bottom hinge. You could still open the door and maintain a good seal when shut.
I went right through the side of my fridge without a hitch. Got some silicone sealant for the holes. I used very thick braided hose, so I’m not too worried about the line getting cut.