Polystyrene box size

So I've got a polystyrene box from my frozen foods order that I'm hoping to turn into a DIY incubator. I am planning to have only one clutch (aiming for a BEL or two).
Ive got all the other supplies, I just don't know if it's really big enough or not!

It's 15x15 inches, 9inches tall.
I'm debating to tape the lid on it, and turn it on its side and making a lid our of the top so it'll be taller for a egg box.
If it's two small, what's the recommended size?
Thanks

https://i.imgur.com/4bhlb1ar.jpg
https://i.imgur.com/8gKMl2Jr.jpg

You can turn that into a ready to go incubator/egg box in a few minutes with a UTH, thermostat, trash bag, pearlite (optional), distilled water, and a piece of light diffuser grating.

Unless your ambient temps are stable 24/7 you would need a half-decent thermostat to regulate temps in such a small area though...:)

That's exactly what I used for an incubator. A bit bigger though... The coolers used to ship fish and stuff to pet stores. 3 strips of 3" heat tape line the bottom with water bottles laid across them for temp stability and a controller. Kept the box at a perfect 89°f all the way through even when I opened it to check the eggs.
Never thought about laying it on its side as a tall box for multi stacking.

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