The very first time I incubated eggs, I used a 20 gallon aquarium. I wrapped foil around the outside, had a small fan on the inside sitting
on the floor to circulate the air, and had 2 60 watt light bulbs in the aquarium hood for heat. I did have to put saran wrap over the
openings on the hood to keep the heat in. I used styrofoam blocks to hold the eggs, just dug some shallow holes with a spoon.
I used an aquarium glass thermometer that attached to the side of the aquarium with a suction cup to check temperatures. Just had
the end of it down about the top of the eggs.
Being a newbie at that time, I didn't think of the humidity. I did have chicks hatch in it.
I had it sitting in the living room and the temps were slightly hard to keep stable with everyone turning on the lamps on the table
where I had it sitting, plus the air conditioning was running.