I started hatching in cartons quite some time ago 1 1/2-2 years and I won't ever go back to not using them. I think it increases my hatch because the eggs that are pipping and zipping aren't constantly being rolled around by the first chicks that hatch. Mine pip, zip much faster than they used to, pop the top of the shell off and push their way out of the bottom. I've never had a chick have trouble or not be able to get out of the carton.
I cut the bottom part of the egg carton off, then I cut the bottoms out of each "holder". The egg sits in what is basically a "band" of egg carton around it. The chick gets a better stance to pip because the egg doesn't fight him/her. Before cartons, I lost chicks who pipped, then rolled with the pip to the bottom and could not right themselves and died in the attempt. I think it makes a cleaner hatch too, as much of the 'gunk' falls into the shell bottom.
I've done exactly two hatches (and a third due this weekend). My first without a carton, second with, and I don't expect ever to go back to hatching without a carton.
There were several advantages:
The eggs pipped & zipped about the same, as far as I could tell. But the newly hatched babies didn't play field hockey with the other eggs, so the later hatchers didn't have any problems from that.
After zipping, the ducklings took longer to get out of the shell, instead of popping out and splatting across the incubator. This may seem like a disadvantage, but it meant that the ducklings were stronger by the time they got out of the shell, so instead of flopping all over the incubator and nearly killing themselves in the effort, their first floppy efforts were contained in the shell and when they finally got out, they were more coordinated and didn't look like they were going to hurt themselves.
It was less messy, much tidier.
I could place the eggs so at such as angle as to be able to watch the entire process and not have to worry that one of the babies would kick it into an inaccessible corner where I couldn't see.
It seems like there were other advantages, but overall I just really liked it. I freaked out with the first hatchling because it was taking so long to get out of the shell--I worried it wouldn't be able to make it--but after that I realized it just takes longer but it's actually worth the wait. I did have one that would not have made it out on its own, but that poor duckling is a cripple to this day (four weeks later), and would have had trouble no matter how the egg had been placed in the bator. Sometimes that just happens.
So I highly recommend it. Basically, you just cut the top off an egg carton, place the eggs in it large end up, set it in the incubator, and you're good to go. This time, I placed a plastic Gladware-type container lid under the egg carton, to eliminate any chance that it would wick moisture from the trays below, because I also have a cloth napkin down in there. Since I'm hatching bantams, I didn't want their tiny feet falling through the wire mesh, and I didn't have any shelf liner handy, so I used a cloth napkin. It's not a very absorbent one, so it's not wicking too badly, but I didn't want to take any chances on having a soggy egg carton.
Yes--pointy end down. And yes, they push themselves out, remarkable as that is. It was counter-intuitive for me, because I've been involved in the birthing community and seen how important gravity is in birthing--you want the baby moving *downward,* not up or sideways. But for chicks it seems to be a good thing to have it struggle against gravity right at the end.
Just remember not to get antsy on that first one--it will seem to be making NO progress for the longest time after it pushes the cap off. But it will get out, and it will be stronger for the effort.
I don't use egg cartons but instead egg tray, basically the same idea. I use the bantam tray which holds 59 eggs..I can put 6 trays in the Dickey or Sportsman. The chick don't seem to have a problem hatching up-right.