I recently bought a pair of zebras that enthusiastically laid their first clutch of eggs, but either were still too unhealthy or too young to know what they were doing and abandoned their eggs, immediately starting another nest.
In desperation, I snatched them up. I read that they can still be saved if you get them early, before one week has gone by, and I researched like mad, trying to learn how to build an incubator with what little I had on hand.
A small cardboard box, thin sheets of shipping foam, umpteen napkins, hand sanitizer, salt water and jute fibers were all I had on hand to build the incubator itself. For heating, all I had was a small under-tank heat mat purchased to incubate my mealworm colony. The heat mat has only two settings: the fire of a thousand suns, and off.
For temperature monitoring, I only have a battery powered baby thermometer(which has a yellow duck head on it and looks ridiculous, by the way). I tried to make a hygrometer the old fashioned way but ALAS!! My hair is too short, my wife's hair is even shorter, and I don't know anyone well enough to ask for some.

There were tons of temperature fluctuations the first night. I had to check the temperature, and correct the amount of padding, distance, air exchange, etc almost constantly. The temperature sometimes would drop down below 32, or rise up over 41, nothing I did seemed to stabilize the temperature, and by the time I figured out to put the three remaining eggs into a fluffed-up bed of jute and got the ventilation and padding JUST right, I was sure I had already goofed up and that the eggs were either frozen or fried by now.
It hadn't been much time, I have been 'sitting tight' on my little eggs for only a few days, so I decided to give it time and see. Every fifteen minutes I would wake up, check the temperature, adjust the nest, and go back to sleep. All day long I would do the same. I turned them every 3.5 hours. I have not slept properly in a very long time, and I was slaving away over eggs I was pretty sure were already dead.
One egg was infertile with a tiny yolk, that one was discarded. Another egg has a normal sized yolk but, as of yet, no further signs of life. The third egg has a blastocyst with no sign of an embryo, and the fourth egg seemed ambiguous, with some dark spots and tiny smears here and there in the yolk, but nothing I could compare to any photos. For all I knew, it was just patches of bacteria feeding on a contaminated egg. I was really dismayed, but kept slaving away.
Why? Maybe I have too much time on my hands, I don't know. But I candled the eggs today to check for signs of bacteria or veins and- to my utter shock, one of the eggs BURST into activity. There is the notorious 'Spider of Life' inside, as well as a tiny little fetus no bigger than a grain of rice.
As I leaned forward, squinting in awe at what I was seeing, shocked and almost unable to believe it was really there, I actually saw a little kick! That was the last straw, I immediately had to put the egg back- I'm not usually an emotional guy, but the sight of it moving around in there, not stuck to the sides, not fried or eaten by bacteria gave me the vapors. I had to have a little cry about it and clean up again before candling the other eggs. (To my credit, I hadn't slept or properly eaten in a long time and even us tough guys gotta get emotional over the miracle of life sometimes.)
So far it's the only one that I'm sure is alive, I've really got to try hard to keep it that way, now. I'm under a lot of pressure! I hope I can keep it alive until I get paid and can order a proper incubator, or at the very least, a hygrometer.
I have no idea what I'm doing. I feel like a tyrannosaurus trying to parent a gecko over here. I could easily swallow this egg without even realizing it.