I have hatched in egg cartons with great success. My bator is full of guineas that went into lock down 5pm on Wed. So far only one has hatched : ( no pips even. I live in Ks and it is so dry here, so I have had trouble with humidity problems this time, but I have been hatching eggs for 3 years now and never this problem. I had all tray full, 4 sponges one in each corner. Finally last nite, when I removed my 1 lonely little keet and added for more sponges. Wondering, if in this time frame, if they have all died in the shell...BOO HOO..... I candled at lock down ,all were good and ready to go...weird. I cut down the sides of carton a little in case they pipped at the side, but not EVEN ONE PIP...had 41 eggs in. Have 3 other incubators with 41 eggs....hope this is not a pattern...grrr...